where to download office 2021 for Mac?

If you are unable to update your Mac OS version, the last version of Office that will work on MacOS Monterrey is 16.88, 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

Office 2021 for Mac is a one-time purchase (perpetual) product and must be installed from the Microsoft account or services page where the license is associated, not from the Mac App Store and not via the Microsoft 365 subscription installer.

Key points for this scenario:

1. Office 2021 vs Microsoft 365 on Mac
   • Office 2021 is a perpetual license and installs the 2019–2021 generation of Office for Mac.
   • Microsoft 365 is a subscription that always installs the latest Office apps.
   • The Mac App Store and the standard Microsoft 365 installer deliver the subscription version only. These are not compatible with Office 2019/2021 perpetual licenses and will keep trying to install Microsoft 365 instead.
2. Why Microsoft 365 keeps installing
   • Apps from the Mac App Store (Word, Excel, PowerPoint, Outlook) and the default “Install Office” flow are designed for Microsoft 365 subscriptions.
   • Perpetual licenses such as Office 2019/2021 cannot activate those Mac App Store apps and will show reduced functionality or subscription prompts instead.
3. How to correctly install Office 2021 on macOS Monterey 12.7.6
   • Sign in with the Microsoft account that owns the Office 2021 license at the Office portal (same account used when Office 2021 was purchased or first redeemed).
   • From that account’s services and subscriptions page, use the installer associated with Office 2021/Office for Mac 2019–2021 (not the Microsoft 365 subscription entry).
   • Download and run that installer on the Mac. This will install the perpetual Office for Mac 2019–2021 build that can be activated with the Office 2021 license.
   • After installation, launch Word from Launchpad, select Get Started, and complete activation with the same Microsoft account used for the Office 2021 license.
4. Do not use the Mac App Store for Office 2021
   • Office apps from the Mac App Store require a Microsoft 365 subscription to create and edit documents.
   • One-time purchase licenses such as Office 2019 Home & Business, Office 2019 Home & Student, Office 2016, and volume licenses are explicitly not compatible with Mac App Store Office apps and must use installers downloaded directly from Microsoft.
5. Monterey compatibility
   • macOS Monterey 12.7.6 can run the Office for Mac 2019–2021 builds that Office 2021 uses.
   • If a Microsoft 365 subscription is also present on the same account, ensure that the installer being used is the one tied to the Office 2021 product, not the subscription entry.

If installation or activation fails after using the correct Office 2019–2021 Mac installer, launch Word from Launchpad, choose Get Started, and follow the activation flow. For persistent activation issues, use the “What to try if you can't install or activate Office for Mac” guidance linked from the Office for Mac 2019–2021 install article.

References:

• Download and install or reinstall Office 2021, Office 2019, or Office 2016
• Troubleshoot installing Office
• Microsoft Office and the Mac App Store
• Microsoft Office activation and the Mac App Store
• Help! I can't get 365 to work. Can I use it on my MacOS or do I need Office? - Microsoft Q&A
• Office running on OS 12.7.6 - Microsoft Q&A