You must register the Azure app with Azure Active Directory (AD).
Important
You can perform the registration manually, as described in this topic, or you can use the custom configuration toolkit, which is available in the custom configuration option and which automates the registration process.
Configure one Azure app per 1000 users up to a maximum of 10 Azure apps. Configuring the recommended number of Azure apps and disabling throttling for Exchange Online will deliver the best possible throughput when performing an initial full backup.
Note
Disclaimer: This procedure is performed using the Azure Active Directory web application. The Azure AD application is subject to change without notice. Consult Microsoft documentation, such as Azure Active Directory Documentation.