In order for remote execution commands to work against workgroup machines, the mgsRET$ share must be added to the domain distribution servers (DS) NullSessionShares list.
This can be achieved via three different methods:-
1. The DS's Local Security Policy tool:
2. Directly manipulating the DS's registry:
Windows Registry Editor Version 5.00
3. Via a domain GPO:
In order for files to be uploaded to a domain DS from a workgroup machine, the DS's reporting location needs to be configured with credentials.