An "Access Denied" error message means that the Windows user account running the backup job does not have access to read the file content.
Current versions of Magnus Box automatically creates a service account with all necessary permissions to read local files. If you are experiencing "Access Denied" errors on Magnus Box 18.6.0 or later, you may be trying to back up a network path that has been mounted as a directory. Please see the "Accessing Windows network shares and UNC paths" section for more information.
If you are experiencing "Access Denied" errors on Magnus Box 18.6.0 or later, and you are certain that you are not backing up a mounted network path, please contact support.