You would require the same computing power you use to browse any other website (The Pi 4 has enough for that), all the computations are made in the RStudio Cloud servers.
Maybe your problem is not the lack of computing power but the browser you are using to open RStudio Cloud in the Raspberry Pi.
Thanks very much, @andresrcs. That's what I had thought.
Certainly, I can access the main Workspace listing all the Projects. However, when I try to open an individual Project, it takes forever and then ultimately fails ('Snaps!').
It may have something to do with our internet connection, which we are trying to improve. I just wondered if anybody else had tried and had a similar or different outcome.