Problems installating Microsoft 2021 using MacOsCatalina 10.15.8

Question

I was advised that Microsoft office 2021 for Mac would be compatible with MacOsCatlina 10.15.8. Made the purchase and completed the downloade - however on attempting to install the message states that I need a MacOS 14 operating system or later. I cannot see how to get the correct version and have tried every possible support or forum structure to try and resolve the issue.

Answer 1

If you are unable to upgrade your Mac OS, the last version of Office that will work on MacOS Catalina is 16.66, that is available on the table on this link to all the downloadable versions from the Microsoft servers.

https://learn.microsoft.com/en-us/officeupdates/update-history-office-for-mac

Answer 2

Office 2021 for Mac is supported on macOS 10.15 Catalina and later, but the installer being used is requiring macOS 14 or later, which indicates it is not the correct build for Catalina.

Use these steps to resolve it:

1. Confirm system requirements and version
   • Office 2021 for Mac supports macOS 10.15 (Catalina) and later, but some newer builds (for example, Office 2024 or Microsoft 365 current builds) require newer macOS versions. The “macOS 14 or later” message means the downloaded installer is for a newer Office build than Catalina supports.
2. Check that the correct product/version was purchased
   • If a one-time purchase of Office was bought, verify that it is the correct platform (Mac vs PC). If the wrong platform was purchased, an “Unsupported operating system”–type error is expected and the remedy is to contact Microsoft support.
   • To verify, sign in to the Microsoft account at the Services & subscriptions page and check that the product name explicitly shows “for Mac” and “For 1 Mac” for a perpetual license.
3. Use the correct installer for Catalina
   • Delete the current installer.pkg from Downloads and empty the Trash.
   • Redownload Office for Mac from the account portal (Services & subscriptions → the Office 2021 for Mac product → Install). This ensures the correct installer for the licensed product is obtained.
   • Once downloaded, install using the standard Mac steps:
     1. Open Finder → Downloads and double-click the installer .pkg.
     2. Click Continue, review and Agree to the license.
     3. Choose the install options and location, then click Install.
     4. Enter the Mac login password when prompted and complete the installation.
4. If the installer still reports an unsupported OS
   • This typically means either:
     • The wrong Office edition (for example, a newer Office that requires macOS 14) is associated with the account, or
     • A Windows-only license was purchased for use on a Mac.
   • In this case, follow the documented guidance: if the wrong version of Office for the hardware was bought, contact Microsoft support to have the license corrected.
5. After successful installation
   • Launch an Office app (for example, Word) from Launchpad.
   • In the “What’s New” window, select Get Started to begin activation and sign in with the same Microsoft account used for the purchase.

If, after these steps, the installer from the account portal still insists on macOS 14 or later, the only supported paths are either upgrading macOS to a version supported by that specific Office build or working with Microsoft support to obtain an Office version whose installer supports macOS 10.15.

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References:

• Download and install or reinstall Office 2021, Office 2019, or Office 2016
• What to try if you can't install or activate Office for Mac
• Unsupported operating system error when installing Office
• Office 2021 license does not work and ist not anymore in the portal listed - Microsoft Q&A
• I just bought Office for Home and Business and now "No license found" - Microsoft Q&A