D365 - You are not authorized to login with your current credentials

If you're restoring Dynamics 365 for Operation database with a backup from another environment, one of the error you might get is "You are not authorized to login with your current credentials. You will be redirected to the login page in a few seconds.".

To fix that, you just need to rerun the "AdminUserProvisioning" tool again.
If you're still getting the error after running the provisioning tool, check the event log.

One of the possible cause would be this database from another environment hasn't been sync with your environment yet, hence, giving some error of this or that field is not found, etc.
Try synchronize the DB, then do an iisreset.