Each installation of Microsoft Authenticator requires registration with the multi-factor authentication service (MFA).
On your computer, visit the Proofup web page, verify / select "Notify me through app", delete stale device(s) from the list, and create a new one by selecting "Set up Authenticator app". This will start the registration process for your new phone and generate a new QR code that your mobile app will use to add the account.
On your mobile device, open MS Authenticator and select add School or Work account. This will open your camera. Let the camera view the new QR code to add the account.
Complete the verification steps presented on the website. Along the way you will see text to guide you. Suggestion… turn off the App Lock option in the application settings until you are accustomed to using MS Authenticator.
Proof Up Link:
Also recommended... Create a Contact card "Microsoft MFA" and add the three phone numbers below.
+1 (866) 539 4191
+1 (855) 330 8653
+1 (877) 668 6536
Creating this contact card will help identify the MFA calls so that they are not accidently blocked as spam.