I’ve moved your post over to the #tinkering section since Roon Extension Manager is not built by us but a 3rd party app, this thread might help with some common settings though:
If you’re just trying to get Windows devices to show as an endpoint, then RoonBridge should work as well, you can download this from here:
Also, you should be aware that Realtek ASIO drivers have caused issues in the past with audio devices appearing in Roon, I’m not necessarily saying that’s the case here, but just something to be aware of.