Everything is setup by following Veeam documentation regarding permissions to grant (https://helpcenter.veeam.com/docs/vbo365/guide/permissions_veeam_backup_account.html?ver=60).
I use Modern Authentication with legacy authentication protocols allowed. All connection and organization parameters are green except the connection to EWS:
"Connect to EWS: The request failed with HTTP status 401: ."
Did someone already face and solve this problem?