Yes. As to the vCAC guide, we created an Endpoint using a Credential to access vCloud Director. Here I used the system administrator of the vCloud Director, a local non-domain account, for the vCAC's Credential. Do you think the vCAC uses this account to perform all actions in the background when executing the workflow?
In my previous tests I used local domain accounts both in vCAC and in vCloud Director, and also used local non-domain accounts both in vCAC and in vCloud Director, but neither worked.