Install the app
Open the Apple App Store or Google Play Store
Search for "Microsoft Authenticator"
Find the app and confirm the publisher is Microsoft Corporation and the icon matches the one shown on the right.
Install the app.
Setup the app
The instructions below outline the setup process for the Microsoft Authenticator app, depending on whether the setup is prompted during a login sequence (registration campaign), or you are setting it up on your own (self-service setup).
Registration campaign
During a login sequence, you may be prompted to update your security information. Follow the prompts on the screen to register the Microsoft Authenticator app.
You will have the option to snooze the setup for 14 days until it is required.
You can watch this video to learn more about registering the Microsoft Authenticator app.
https://youtu.be/k0oiKQK3LjQ