Microsoft Teams Room Licensing Changes July 2023
As of 1st July 2023, personal users will not be able to sign into Microsoft Teams Room devices, so you either have to make a new resource mailbox for the user or add a Teams Room Standard or Pro license to the users account.
Find Teams Rooms devices with unsupported licenses - https://learn.microsoft.com/en-us/mic...
FAQ Document - https://aka.ms/MTRLicenseNotice-EFAQ