To sign in using Azure Active Directory, your RPI server must have been configured to support this feature.
In addition, an Azure Active Directory user with an email address matching the RPI user as which you intend to sign in must exist and must have been granted appropriate privileges to access RPI.
To sign in using Azure Active Directory, select this option at the Sign in using chooser. When you do so, Username, Password, Forgot password? and Save credentials… are hidden.
On clicking Sign in, one or more Microsoft Sign In dialogs are displayed (depending on whether your credentials have been cached previously). Enter your credentials (if required) and follow the instructions therein. Upon successful authentication of the supplied credentials, the Sign In dialog is removed from display and, after a short delay, the RPI Sign in dialog is replaced with the Home Page (if you are able to access multiple RPI clients, you will first be asked to select one).