I'm not 100% sure exactly what configuration you are setting up....when you say 'install the Agent', do you mean install our nworks Collector? Are you installing our Collector on the VC server?
Because all nworks components can be installed remotely on a different server from VC (e.g. on a VM which IS in the domain). Then you can connect remotely to VC (using a local username in our Add Connection wizard).
Also - you may be getting the "User is not allowed to access the Management Center" error during setup because - after installing nworks Management Center, and creating the new local group for service & user accounts - you need to log off, and log back on, then complete the installation of other nworks components (UI, and Collector).
This is a Windows issue - you must log off and on again in order to 'activate' your new group membership. See our release notes for details.
Let me know if that helps! If not -please send more details of the exact configuration you are setting up,
Vice President, Product Management