How to run SNAPHU unwrapping on RUS?
There is a quickstart guide on the RUS page.
Getting started – Research and User Support (rus-copernicus.eu)
I think this will help you. If you still have questions you can contact the RUS user support.
I guess they can better help you.
In general it should work the same as on your local system. Because you get a virtual machine on which you can run SNAP. All special questions are better discussed with the RUS team.
There is also a RUS forum where you might find similar topics on this: RUS user forum