Hi Katrin, thanks for reaching out.
It sounds like the account is stuck in a loop because Microsoft thinks it belongs to a child, which usually happens when the birthdate wasn’t entered or shows the user as under 18.
The system then asks for parental consent, but instead of completing the process, it keeps sending you back to the sign-in page.
A quick way to start is to clear the browser’s cache or try a different browser, then check if the birthdate on the account is correct by going to account.microsoft.com/profile.
If it’s wrong, update it and save. If the page won’t load or the loop continues, you might need to sign in at family.microsoft.com and either approve the account or remove it from the family group.
Can you confirm if you have access to another device or browser to try these steps?
Also, do you know if the account is part of a Microsoft Family group?
Regards,
Aron