I don’t think folder navigation is available on JRemote.
It's basically an extension of the OS functionality on the PC where JRiver just uses the underlying folder structure within JRiver. I don't think that's available on JRemote.
Can you elaborate ? I can navigate folders through the JRemote app (android). For example under Audio, i have the following : Files, Album, Artist, Genre, Recent. Choosing Files gives the folder tree.
This view is customizable, so probably you have got the files view disabled. Check the options on the server. There is a seperate set of options for remote access.