I am unable to log in using specific credentials on any IOS device. I am able to log in successfully on an Android device (Galaxy 7) using these credentials. When trying on IOS, i often got a 401 unauthorized, (Ping logo at the bottom of the page). I have tried with and without Azure Authenticator installed and it makes no difference.
I was able to use an account from a different company on the IOS device and that account does log in, and automatically places the account in the Azure Authenticator App also.