Hi
I do not know very much about Rsmembership but I imagine it would need a special plugin. The one they have for Zoo looks something along the right lines. However they say:
QuoteNormally you don't necessarily need such a plugin as you can manually specify the URLs RSMembership! should restrict. Since some cases require to use wildcards ({?}, {*}) to specify a particular range of URLs, why not use the integration plugin instead to perform ZOO content restriction in simpler steps.
You would need to ask the rsmembership people if you need a plugin as they are the only ones who know how their component works.
jD does have an example plugin "jDownloads Example" which would no doubt assist.
Colin