How to Download and Install Mac Software: App Store, DMG, PKG Installation Tutorial and Fixes for Apps That Won’t Open or Install

You downloaded a Mac app, but the file or security prompt doesn’t make it clear what to do next.

Fastest safe fix: identify the download source and file type first. Get App Store apps through the store, open a DMG and follow the developer’s installation instructions, and run a PKG only when you trust its source. If anything fails, check the warning, macOS compatibility, permissions, and download integrity before trying again.

This guide is for first-time Mac users choosing between App Store, DMG, and PKG installation; anyone troubleshooting an app that won’t open or install; and people handling software on a remote Mac.

Choose the installation route before downloading

Start with the app’s official product page or the App Store. Check that the app name and developer match the software you intend to install. Avoid download buttons on pages that do not identify the publisher or explain what the file does. Apple recommends obtaining apps from the App Store or directly from developers and explains how macOS evaluates apps from other sources in its guide to downloading apps safely.

The file extension helps you identify the next step, but it does not prove that a download is safe:

App Store: The app is listed and distributed through the store. Use the store’s own Get, price, or download control.
DMG: A disk image file, usually ending in .dmg. Opening it mounts a volume in Finder. The app may then need to be copied to Applications, but follow the developer’s instructions because the contents and process vary.
PKG: An installer package, usually ending in .pkg. Opening it starts an installer that may place files in different locations or request administrator authentication.

These are different delivery formats, not interchangeable install buttons. Apple’s developer documentation describes packaging Mac software for distribution, including installer packages and app bundles; use the publisher’s instructions to confirm what a particular package is expected to do (Apple’s software packaging guide).

Before downloading, check three specific requirements:

Minimum macOS version: Find the app’s stated system requirement on its store listing or developer page. Compare it with your installed version; Apple’s macOS version information can help you identify your system.
Required storage: Check the download or installation instructions for the app’s storage requirement, then compare it with available space on your Mac. A large download may also need extra room while an installer unpacks files.
Account permissions: Confirm whether you can install apps for your account or whether the installer may ask for an administrator name and password. Do not assume that every app or Mac will show the same prompt.

Which route should you choose?

Use these decision branches to select a route before you open a downloaded file:

If the app is available from the App Store and the listing matches the intended developer, install it from the store. Otherwise, use the developer’s official download page.
If the official page supplies a DMG, open it and follow the included directions. Copy the app to Applications only if the developer instructs you to do so.
If the official page supplies a PKG, run the installer and read each screen before continuing. Stop if the publisher or purpose is unclear.
If a warning says the app can’t be verified, is damaged, or is incompatible, do not disable security checks just to force it to launch. Check the exact message and the developer’s support information first.

Workflow fit, not security certification: App Store — easiest when listed; DMG — suitable when the developer provides a clear copy-and-install process; PKG — suitable when the software requires an installer. The format alone cannot tell you whether a file is trustworthy.

Install from the App Store

How do you download an app from the App Store?

Open the App Store and search for the exact application name. Check the developer, description, and compatibility details before selecting Get, the displayed price, or another available download control. The wording and whether you see a download button can vary with the app, your account, and macOS. Apple’s App Store download instructions explain the standard store flow.

After the download finishes, look for the app in Launchpad or the Applications folder. Open it from there. If it does not appear, search for its exact name in Finder before starting another download; the app may already be installed in a location you did not expect.

If the download does not start or stalls, check the network connection, sign-in state, and whether the app is currently available to your account or region. Then try the store’s download control again. Avoid deleting account data or changing security settings to fix a store download. Apple’s App Store download troubleshooting steps cover common account and download problems.

Fit rating: High for a listed app when you want the store to handle its download and installation. Conditional if the app is not listed, is unavailable to your account, or the publisher only distributes it directly.

Open a DMG and install the app

How do you install a Mac app from a DMG?

First, confirm that the DMG came from the developer’s official site. In Finder, open Downloads and double-click the .dmg file. macOS may show a mounted disk image in a Finder window or in the Finder sidebar. Read any included instructions before opening files inside it.

A common process is to drag the app icon into Applications. That is not universal: a developer may provide a different installer, extra components, or a setup document. Follow the instructions packaged with the software rather than assuming every DMG uses the same layout. Apple’s Mac download and installation guidance describes the general process, while the software publisher’s notes apply to that specific app.

When copying finishes, open Applications and check that the app is there. Eject the mounted disk image in Finder when you no longer need it. The DMG file in Downloads is the installer image; it is not necessarily the installed app. Keep it only if you expect to need it again.

Do not launch unrelated files just because they appear beside the app. If the disk image contains an unexpected script, helper, or second installer that the developer does not document, stop and verify the download with the publisher. A familiar filename or icon does not confirm the source.

Fit rating: High when the developer provides clear instructions and a standard app to copy. Conditional when the image contains several unfamiliar files or requires steps the publisher has not explained.

Run a PKG installer

How do you run and finish a PKG installation?

Use a PKG only when you downloaded it from a source you trust and the publisher identifies it as the correct installer. In Finder, locate the .pkg file, open it, and read the installer’s introduction and any license or destination information. Select only options that match the software you intend to install.

The installer may ask you to authenticate as an administrator. Whether that happens depends on the software and system settings. If you do not have the required credentials, do not try to bypass the prompt; ask the Mac’s administrator or the software’s support team what access is needed.

Wait for the installer to report its result. If it completes, follow its instructions for launching the app or checking the installation location. Some installers do not place the main app directly in Applications, so use the publisher’s documentation to confirm the expected result. If the installer stops, record the complete message and the step where it stopped before trying again.

Apple’s packaging documentation explains why a package installer can perform a different distribution process from copying an app bundle out of a DMG (Mac software packaging). Do not run a second copy of the installer from a different download source until you know why the first attempt failed.

Fit rating: High when the developer requires an installer and documents its options. Conditional if you lack administrator access or cannot verify who supplied the package.

Troubleshoot an app that won’t open

What should you do when macOS blocks an app?

Record the full warning before acting. “Can’t verify,” “damaged,” “not supported,” and a request for a password are different clues. They can point to a source or security check, a damaged download, a compatibility issue, or an account permission problem. A partial paraphrase can hide the information you need to choose the right fix.

Use this order:

Check the source. Confirm that the download came from the App Store or the software developer’s official page. If you cannot confirm the publisher, remove the installer and obtain the app from a trusted source.
Check the system requirement. Compare the installed macOS version with the app’s stated minimum. If the app requires a newer system, ask the developer which versions it supports before changing the Mac.
Download a fresh copy if damage is reported. Delete the questionable installer, return to the official source, and download it again. Do not reuse a file that repeatedly produces a damage warning.
Follow Apple’s instructions for the exact warning. Apple documents what to do when a Mac cannot open an app. The appropriate action depends on the message and the app’s source.
Check account access. If the app or installer requests credentials, confirm whether you are using an administrator account or ask the Mac’s administrator for help.

Do not treat every security message as an obstacle to remove. Avoid instructions that tell you to turn off Gatekeeper or paste an unverified command into Terminal. If the warning remains after you verify the source and compatibility, contact the developer. If the message appears to concern macOS rather than the app, use Apple Support. Apple’s broader app download safety guidance explains why source verification matters.

Troubleshoot an installation that fails

How can you check permissions, compatibility, and the installer?

Diagnose the failure at the step where it occurs. A store download that never finishes, a DMG that will not mount, and a PKG installer that stops partway through need different checks.

Check whether the download completed. Compare the file shown in Downloads with the expected file from the developer’s page. If the file is missing, unexpectedly small, or produces an error when opened, download it again from the official source.
Check available disk space. Compare free space with the installer’s stated requirement. If the requirement is not published, do not guess that the Mac has enough room just because the download fits; an installer may need additional space to unpack or place files.
Check account permissions. If a PKG asks for administrator credentials, use an account authorized to install software or ask the Mac’s administrator. Do not attempt to work around the permission prompt.
Check macOS compatibility. Read the developer’s minimum system requirement and compare it with the Mac’s installed macOS version. If the app is not supported, stop and ask the developer about a compatible version.
Match the fix to the file type. For App Store failures, check network and account status, then use Apple’s store download troubleshooting guide. For a DMG that will not open, replace it with a verified download and check the developer’s instructions. For a PKG that stops, save the full error and report it to the publisher.
Stop if the warning changes or repeats. Do not keep opening a file that is reported as damaged, from an unidentified developer, or incompatible. Replace the installer from the official source or ask the developer to confirm the package.

This sequence separates the main variables: download integrity, storage, account access, and operating-system compatibility. It also gives a support team useful details: the file type, exact error, and the step where installation failed.

Check the target Mac when working remotely

The same App Store, DMG, and PKG distinctions apply on a remote Mac. The extra risk is installing on the wrong device. Before opening an installer, confirm that the remote session is connected to the intended Mac and that the Finder window or desktop belongs to that session. If you switch between local and remote screens, verify the target again before entering credentials or approving an installer.

Remote access does not guarantee administrator rights, app availability, or compatibility. Those depend on the actual Mac, its account permissions, the software source, and the app’s requirements. Do not assume a remote environment has a particular setup unless its provider documents it. If you want to understand who operates the service before evaluating a remote workflow, read VPSSpark’s company information.

A remote Mac can be useful for a temporary installation test or a task that specifically needs macOS. It is not automatically the right choice for a long-running workload that requires stable access, and it will not replace a local Mac when you need physical ports or direct access to local files. Consider the task, access method, and permissions before moving an installation workflow to another device.

Finish with a source-and-error check

Before retrying, match the file type to its install route: App Store means install through the store; DMG means open the image and follow its instructions; PKG means read and run the documented installer. Then verify the developer, macOS requirement, available space, and account permissions. Keep the exact error message. If it still does not fit one of those checks, stop and ask the software developer or Apple for guidance rather than weakening macOS security.

If you only need a temporary Mac environment to test an installer or complete a macOS-specific task, compare that option with using your own Mac or an existing environment first. A remote Mac adds access and permission checks, and it is a poor fit when the job depends on a physical connection or uninterrupted long-term use. For a short, clearly scoped task, compare the available remote Mac options—provided you confirm the target device and install only software from a source you trust.