How do I fix the error “Microsoft Doesn’t Allow Editing on a Mac”?

You may perform the following steps:
Click the “Use another account” button and sign in again. Once you sign in, check the notification, restart your Mac if you are being told to do so.

You can also try the below steps once you have logged in to office:

1. Log in to Office 365 portal (portal.office.com)
2. Settings>Office 365>subscriptions
3. Under Licenses section, make sure you have been assigned the “The latest desktop version of Office”

If so, please follow the steps below:

1. Make sure you are connecting to the Internet.
2. Sign out account and Quit Office apps.
3. Go to the Library folder and open Group Containers. Ctrl+click each of these folders if present, and Move to Trash. UBF8T346G9.ms UBF8T346G9.Office UBF8T346G9.OfficeOsfWebHost
4. Restart Office then sign in with your account