Open the Microsoft Authenticator app on your phone and tap the Home button in the bottom left corner of the screen. For security purposes, you may be prompted to enter your phone’s unlock code or use biometrics to unlock and open Microsoft Authenticator.
Open the app's Home screen
On another (or the same) device, sign in to your Microsoft Work Account with your username and password.
Sign in to your Work account on another (or the same) device
On the device where you are signing in, notice your two-digit code displayed in the "approve sign in request" pop-up. If you are on your computer, select the "don't ask again…" option.
Remember your code
Return to the Microsoft Authenticator app, enter your two-digit code, and then tap “Yes.” You may be prompted again to enter your phone’s unlock code or use biometrics, like in the earlier step.