An integrated threat protection solution designed to detect, investigate, and respond to cyber threats across Microsoft 365 services.
You fail to mention what Office version & licence type or what win version
If a PC and office desktop start with this,
Restart the PC, once fully loaded, repair Office,> Apps & Features>Select Office your version>Modify /Repair, once the repair completes re-test (Quick repair)
O365/Office when installed under a Win user admin account, and run from that admin account, auto logs in when the PC is started. There is no separate login for any component.