Remote submission - cylc: line 0: exec: cylc: not found

I’m now running into this error:

Unexpected key directory exists: /home/rcs001/cylc-run/batch-test/run9/.service/client_public_keys
  Check global.cylc install target is configured correctly for this platform.

This question has been addressed here: Setting up a Platform Config for machines that share a home directory - #2 by hilary.j.oliver