Known Issue: Your account doesn't allow editing on a Mac.

Some users reported receiving the message "Your account doesn't allow editing on a Mac. To learn more, contact your admin about your Office plan" after launching one of the Microsoft 365 for Mac apps (formerly Microsoft Office) on their Mac computer. The app then runs in is in read-only mode. 

If you are affected by this issue, try this first:

1. Click the app name in your finder bar (e.g. Word, Excel, PowerPoint)
2. Click Sign Out. 
3. Restart the app, and try to sign-in again.

If that does not resolve the issue, perform the following steps:

1. Launch each Microsoft 365 app installed on your Mac, click on the application name (e.g. Word) menu and choose Sign Out. Then quit the application.
2. In the Finder, click on the Go menu and choose Go to Folder
3. In the box, type: ~/Library
4. Click on the Group Containers folder
5. Locate the following three files/folders and drag them to the Trash
   • UBF8T346G9.ms
   • UBF8T346G9.Office
   • UBF8T346G9.OfficeOsfWebHost
6. Empty the Trash and launch an Office application to check if you can now edit documents.

If that does not resolve the problem, perform a full uninstall of Microsoft Office using the instructions from Microsoft here. Once Office is uninstalled, reinstall it from https://portal.office.com