Cause
Unknown
Resolution
1) Open Credential Manager:
2) Remove any saved credentials with O365, TTU, Microsoft, or Office on both Web Credentials and Windows Credentials.
3) Open a Microsoft 365 app and check to see if your software still needs to be activated. If so, attempt activation again.
Workaround
De-activate a previous installation by following the directions at https://support.microsoft.com/en-us/office/deactivate-an-installation-of-office-767e3560-96ed-4b1c-806d-2fe01c529b1b.
NOTE: It can take up to 72 hours for Office to detect that you signed out remotely.
OUTCOME
You are able to activate your Microsoft Office product.