Using classic Outlook for Windows in business environments
Having the same issue, and it's completely idiotic. All our users we blocked from logging in to download this stupid Microsoft Authenticator App. The settings for admins are so complicated that it's impossible to figure out what's going on. Why is SMS or Call not enough as an MFA?? Insane.
Pretty simple. Microsoft has to pay per SMS message sent. The process is really not that bad, and there is also an App for PC and Mac