Adding Organizations with Modern Authentication and Legacy Protocols
When you add an organization using the modern authentication method with legacy protocols allowed, you use both Veeam Backup account and Azure AD application for authentication. Veeam Backup for Microsoft 365 uses Veeam Backup account and an application to establish a connection to your Microsoft 365 organizations with disabled security defaults and maintain data transfer during backup and restore sessions.
Adding Microsoft 365 organizations using modern authentication with legacy protocols allowed is not supported for Microsoft Azure China region.
To add a new Microsoft 365 organization to Veeam Backup for Microsoft 365, check prerequisites and do the following: