Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello,
If you’re running the latest version of macOS and the Microsoft 365 apps but still see an “Activation” error, first make sure your subscription is active under your Microsoft account here.
https://account.microsoft.com/services
If the subscription is active, use the Microsoft Office License Removal Tool here to completely remove any previous Office license files from your Mac, then reactivate Office 365 apps using your Microsoft account.
How to remove Office license files on a Mac
Let me know if you still need more help.