Hi @Snowman,
I do not think you can do it simply because your CE Studio Named user license has to be connected to Cloud Orchestrator and send heartbeats vis the robot service.
In other words, You can connect the CE Studio to your enterprise Orchestrator but this will de allocate your cloud Studio license and you will need another named user license from your enterprise orchestrator.
So with those two reasons, what you are looking for cannot be achieved.
Some releases before, the customer portal was not available, so we used to download Studio Msi from our community edition and then allocate license to the community edition of Studio in our On-Prem orchestrator which consumed one of our Named user (Automation Developer) license.