Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Known issue.
My fellow VM Emily has written a pretty solid answer on this:
https://yourwindowsguide.com/2026/10/office-2021-for-mac-deactivated-after-update.html
Follow the steps in Microsoft’s guide: Remove Office license files on a Mac.
Concurrently, Download the appropriate installer package and install Office. Also, a direct download link for your convenience is here:
Download Office 2021 for Mac older version 16.114.1
Select the earlier version instead of reinstalling 16.114.1, which is associated with the reported issue.