how to regain access to my school outlook email after upgrade to a new iphone (MS authenticator is no longer availabale)

School email (not personal email) is on office 365 and use MS authenticator as MFA. After receive a new iphone and transfer/upgrade to it (old one has a backup on icloud but wiped out on the phone), I find unable to access all office suit, no school email, one drive etc since everytime it would ask for the code on MS authenticator. It would have no problem if we still had the old iphone present without wiping it out. On the new iphone and existing old iphone restored from icloud backup, neither would receive the authenticate code or the verification code. Seems MS authenticator is the only MFA setup by default for school/work email. If upgrade to new iphone + wipe out the existing one, you are screwed. Is there a way we can regain the access, so far

1. restore from backup, not working since by default, the authenticator doesn't backup to icloud at all.
2. remove the app and reinstall it, not working
3. remove id from the app and try to add the email back, not working.

Anyone has any workable solution other than go back to the school IT admin?