Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hi Joshua,
As per the description, I understand the scenario you are encountering with that enter the email will be automatically changed to a different email address that prevented you to login correctly.
In this situation, please don't worry and let's try the official tool from How to remove Office license files on a Mac - Microsoft Support that can reset the credentials. After running it, you may restart Office apps and try if you can login successfully.
Please correct me if I made any misunderstanding and I will be here waiting for your updates.
Appreciate your time and patience. Hope you a nice day and stay safe!
Best Regards,
Mia