For more information about how to download and install the app, see Download and install the Microsoft Authenticator app. Microsoft Authenticator also supports cert-based authentication by issuing a certificate on your device. You will need to register your device to your organization through the app and add your work or school account. Presumably because it was not finding the matching account in the app. On the Start by getting the app page, select Download now to download and install the Microsoft Authenticator app on your mobile device, and then select Next. Sometimes your work or school might ask you to install the Microsoft Authenticator when accessing certain files, emails, or apps. Outlook Mobile was prompting to 'switch to authenticator' and then once we were IN authenticator it offered the same prompt to 'Switch to authenticator' again, endlessly. I had a user that migrated to a new phone, and the MS Authenticator App picked up on the Office 365 account from the other apps on the phone, and the email showed up as a 'Connected Account' when we tapped into the account but would not receive notifications or provide One-Time Passcodes for the account, even though it was listed. Its specifically designed to add security for Microsoft accounts, but also provides functionality for other accounts such as Facebook, Quickbooks, and Twitter. I just want to throw out there (since I found this while searching, and I wouldn't want to leave a DenverCoder situation) that the user may not realize their phone is not connected to the account properly, because the MS Auth app doesn't look particularly different in some cases. Microsoft Authenticator is a safe application to use that doesnt require a QR code, unlike the Google Authenticator app.

Microsoft authenticator app install