Microsoft autoupdate problems

The Microsoft AutoUpdate app is in /Library/Application Support/Microsoft and is triggered by /Library/LaunchAgents/com.microsoft.update.plist.

I have Office 2021 for Mac installed and it just works. I never am aware that Microsoft AutoUpdate runs until I launch an updated version of one of the applications and Apple's GateKeeper scans it for two seconds.

I suggest that you uninstall Microsoft Office using Microsoft's Uninstall Office for Mac. Reboot your Mac and then reinstall Office 2021 for Mac (using a custom installation if you don't want Outlook, OneDrive, Notes, etc.) and apply the product key. Then leave it alone (other than preferred application settings) and it should work fine like my installation.

It still remains important to continue updates in Office as Microsoft may make changes to Office that accommodate updates in macOS, another area to remain current too. When you get out of sync, things may not behave as you expect.