In order to find logs for CloudSync for DSM 5.0, SRM 1.0 and above, please follow these steps:
1. Log into DSM/SRM as the default 'admin' account.
2. Click on the Main Menu button in the top left corner of the screen, Support Center, then Support Services, and click Generate Logs. (Make sure to check the box to include CloudSync or Hyper Backup logs).
3. Then, download and save the debug.dat file.