Hello Tyler Spraggs,
Thanks for your question.
You are receiving the message because the account you are using to sign in does not exist in the tenant. It can be as a result of different reasons.
I will recommend you clear the browser cache/cookies or try signing in a different browser/Private browser. Sometimes cached accounts can cause this error.
If it is an application within Azure you want to access, you may need to request to be invited from the owner of the tenant not MS. If you're unsure of the correct tenant or don't have the appropriate account, reach out to the administrator of the Entra tenant you're trying to access
You can mark it 'Accept Answer' and 'Upvote' if this helped you
Regards,
Abiola