Unable to use Microsoft functions

The screenshot shows Unknown error 0x0 while Excel is activating on macOS. For Microsoft 365 on Mac, the supported self-help path is:

1. Check whether macOS is still supported Microsoft 365 for Mac supports the three most recent macOS versions. If the MacBook Air is on an older macOS, Office can stop working correctly or be reduced to limited functionality.
2. Update Office from inside an Office app Open an Office app and go to Help > Check for Updates to launch Microsoft AutoUpdate, then install all available updates.
3. Make sure the Office apps are in Applications In Finder, open Applications and confirm Word, Excel, and the other Microsoft apps are there. AutoUpdate depends on the apps being in Applications to detect and update them correctly.
4. Sign out and sign back in In an Office app such as Word, select the account name or profile icon at the top, choose Sign out, then Sign in again with the Microsoft account that owns the subscription.
5. If the subscription is active but activation still fails, reinstall Office for Mac Uninstall Office for Mac, then reinstall it from the subscription page of the Microsoft account, and run Help > Check for Updates again after reinstalling.
6. If the issue continues, use Microsoft support entry points For sign-in problems, use the Start sign-in helper. For installation, activation, or technical support, use Get Help on the web.

Microsoft support contact in the provided material does not list a public support email address. It directs users to the support tools instead.

References:

• What to try if you can't install or activate Office for Mac
• Contact Microsoft customer support
• my brand new 365 account is not working at all - Microsoft Q&A
• Unknown Error 0x0 or License not found error in Microsoft 365 or Office running on macOS