Hi @Michael Francis ,
you have to take a look on the Facebook website how to deal with MFA issues:
Using an authentication app for two-factor authentication on Facebook
Troubleshoot login with two-factor authentication on Facebook
Facebook is providing the MFA feature and the MS Authenticator app is just "the middle part" that gets and send the MFA approval from Facebook.
(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Regards
Andreas Baumgarten