Hi @Rúben Costa ,
if you enter the error code 500571 here https://login.microsoftonline.com/error you get the following reason:
Error Code: 500571
Message: The guest user account is disabled.
Remediation: The guest user object in Active Directory backing this account has been disabled. An admin can re-enable this account through Powershell: https://learn.microsoft.com/powershell/module/addsadministration/enable-adaccount?view=win10-ps
It looks like your account is a guest in an Azure AD tenant and disabled.
----------
(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Regards
Andreas Baumgarten