Found out that "Notification through mobile app" and "Verification code from mobile app or hardware token" under "Service settings" was not ticked of for some reason.
Ticked them of, and now it works.
This browser is no longer supported.
Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.
We want to set up "Authenticator app" as an additional security verification on an account at a customer, but this is not an option on the "Additional security verification" page for the user we want to add this to. What can cause this?
FYI: The tenant do not have Modern authentication enabled
Found out that "Notification through mobile app" and "Verification code from mobile app or hardware token" under "Service settings" was not ticked of for some reason.
Ticked them of, and now it works.