Dear @awi
Thank you for reaching out Q & A Forum!
We understand that you have a trouble with Authenticator app and unable to set up MFA for your school account.
As forum moderators, we don’t have access to the detailed system needed to troubleshoot this effectively due to privacy and security constraints. To quickly resolve this and regain access, the most effective step is contacting your school's IT Support or Help Desk directly, as they are best equipped to address and resolve this type of issue efficiently.
We suggest you contact your Global Administrator to ask them to follow this article to proceed to reset your 2FA so that you could re-register again: Manage authentication methods for Microsoft Entra multifactor authentication - Microsoft Entra ID | Microsoft Learn
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