How can I stop the prompt "Do you want Microsoft Office to automatically update?"
Copy-paste from answers.microsoft.com.

The nagging is sent by Notifications in the macOS and can be turned off in System Preferences--&gt;Notifications as mentioned above.
This has no effect at all on when and how Microsoft AutoUpdate works. I just ran MAU to test this. You can still choose &quot;Automatically Check,&quot; which will ONLY check (not download and install) and then will alert you if there are updates.
Disabling MAU in Notification Center has no effect on this. I disabled it and the nagging is no longer there. MAU provides its own pop-up notification WITHOUT triggering  macOS notification.