SC is getting error from ONTAP. What could be happening is that you are using snapmirror and what happens in this case is snapshots get locked for a little while. Usually folks add sleep NTAP_POST_DATA_TRANSFER_CMD01=sleep 60. If that isnt case there may be some other issue, I would open an NGS support case as there could be something else non-SC related happening.
Anyway for all pre / post cmds default behavior is send cmds to SC Agent. If you want to run them on server you need to specify SERVER: or you can specify AGENT: for agent. There is also CLONETARGET: if you are using a second agent for cloning.
You are also using windows so I think you need POST_NTAP_DATA_TRANSFER_CMD01=SERVER: cmd /c sleep 60 OR POST_NTAP_DATA_TRANSFER_CMD01=SERVER: "cmd /c sleep 60" OR POST_NTAP_DATA_TRANSFER_CMD01=SERVER: "sleep 60"