Rennnat I think there are two possible causes:
a) The app itself has not been set up according to your organization's requirements. Some require Microsoft Authenticator to be set up with specific steps, such as that you have to scan a QR code that has been generated on a compliant device. They may disallow directly signing in to the app with your work account.
You could try uninstalling the app completely, and then carefully follow the instructions provided by your organization on how to set it up. This is assuming that your work is even providing you with instructions! If they don't, ask them.
or it could be
b) Your organization has set up policies in Entra ID to disallow devices and IP addresses that don't meet certain requirements, and you are triggering one or more of these flags somehow. It's hard to know for sure what these actually are without asking the admins of these policies. First, I recommend following a).