Teams lässt sich nicht einrichten

jenswohlfeil Hello, these are the most common scenarios for the message https://docs.microsoft.com/en-us/microsoftteams/troubleshoot/teams-sign-in/someone-has-already-setup-teams

But it could be that a user has signed up for a self-service subscription and then you need to perform an internal takeover https://docs.microsoft.com/en-us/microsoft-365/admin/misc/become-the-admin?view=o365-worldwide