Explanation
If you must specify user credentials to access the shared folder, select the This share requires access credentials check box. From the Credentials drop-down list, select a credentials record for a user account that has Full Control permissions on the shared folder. To access the SMB share, you must use an account that meets either of the following requirements: If you only plan to back up the share, you can use an account with read-only permissions. If you plan not only to back up the share, but also to restore files to it, use an account with read/write permissions.https://helpcenter.veeam.com/docs/backup/vsphere/file_share_backup_smb_share_path_credentials.