Can't connect Orchestrator to a Workgroup PC

I would like to ask what would be the username to use in setting up robot in Orchestrator if the PC/Machine belongs to a workgroup and doesn’t have domain. I was able to setup orchestrator successfully on my other machine because they have domain name which is dir\username, however on my new machine I found out that it belongs to a workgroup with no domain. If I type in whoami in CMD, what I’m getting is the hostname\username and orchestrator is not allowing it and always result to invalid machine key.