Unknown error occurred

For Microsoft 365 activation, no activation code is required for a subscription. Activation is done by signing in with the Microsoft account that has the active subscription.

For error 0x0 on Mac, use this path:

1. Confirm the correct account is being used.
   • Sign out of Office, then sign in again with the Microsoft account associated with the subscription.
   • Check the subscription at https://account.microsoft.com/services.
   • If an Office or Microsoft 365 license appears there, that is the account to use for activation.
2. Reset Office activation credentials on the Mac.
   • Open Spotlight.
   • Search for and open Keychain.
   • Search for Office.
   • Delete the data license file.
3. Run the Microsoft 365 Activation troubleshooter.
   • Use the Microsoft 365 Activation troubleshooter at https://aka.ms/SaRA-OfficeActivation-sarahome.
4. Update Office.
   • If Office is outdated, update it using Microsoft AutoUpdate, then reopen Word, Excel, or Outlook and sign in again.
5. If the issue started after a renewal or account change and the subscription does not appear correctly, contact Microsoft support through the official support flow.
   • Go to https://support.microsoft.com/contactus/
   • Search for Contact support or Chat with an agent
   • Choose Microsoft 365 and Office and follow the prompts for chat or callback options

About the $5 charge: the provided material does not show any Microsoft activation support fee for resolving this issue. Use the official Microsoft support contact flow above rather than third-party paid support offers.

References:

• What to try if you can't install or activate Office for Mac
• I can't activate my microsoft office - Microsoft Q&A
• Is there a live person to contact or call? - Microsoft Q&A
• Microsoft 365 subscription won't activate - Microsoft Q&A