You may get the following exception when turning off the "Use Windows Task Scheduler" option:
Windows Task Scheduler
System.UnauthorizedAccessException: System.UnauthorizedAccessException: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
This may indicate that the "Run with highest privileges" option of the SyncAndSaveTimer task has been set. This option must be manually turned off before Sync & Save can configure the SyncAndSaveTimer task.