How to add organizations with Modern Authentication and Legacy Protocols at Veeam Backup for Microsoft 365
You will use both Veeam Backup account and Azure AD application for authentication if you add an organization using the modern authentication method with legacy protocols allowed. 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.