When setting up a new Scorch server (yes even 2016) you get the message ‘access denied’ when anyone but the person who set up the server tries to access the runbook designer.
When you check the event viewer on the runbook server you also see permission denied errors for DCOM.
I found a KB on the MS site that covers the process to add access.
However the service to restart is not what is mentioned in the kb article. (at least on 2016) I found the best option is to go ahead and reboot the scorch server after making the changes mentioned in the KB.