When signing into your Microsoft 365 account, you may be prompted to setup an "Authenticator" app, as shown in the screenshot in section 1 below. Please use the following instructions to set this up using the Microsoft Authenticator app on your mobile device.
1. Click Next when prompted on your PC, as shown below.
2. Search for the Microsoft Authenticator app on the app store of your mobile device, then install it. Once installed, click Next on the PC, as shown below.
3. Open the Microsoft Authenticator app on your mobile device, tap Allow when prompted to allow notifications, and tap Accept to accept the terms. Tap Continue on the "Help us improve Authenticator" screen on the mobile device. Back on the PC, click Next on the screen, as shown below.
4. On the Microsoft Authenticator app on the mobile device, tap Scan a QR code, then scan the QR code shown on the screen of the PC (the QR code is removed from this example screenshot).
5. On your mobile device, there should be a notification asking you enter a number. Look at your PC's screen, and find the randomly generated number like the "50" shown below. Enter whatever number is shown on the screen into the Authenticator app on your mobile device, then click yes.
6. You should now be all set. Click Next on your PC, as shown below. On the following screen, click Done. This number matching used in step 5 will be used going forward when you sign into your Microsoft 365 account.