No Authenticator App Code on mobile and no chance to log in the business / school account

Question

Hello,

I am Freelancer and have the business/school account (free) . I don't receive the code in the authenticator app on my mobile and so cannot login.

This prevents me from using MS Teams properly with clients and so I don't know how I should upgrade the account (that I am supposed to do until April 12th) if I am not able to acccess?

I already deinstalled the Authenticator App on my mobile but if I am asked to reinstall, I need to login first which I cannot do because of the code... so infinite loop...

I am also asked to contact the admin, but I can't because it is just me..

Is there a solution for this problem? After many hours with the MS support chat I am now ending here quite frustrated ...

Many thanks for support