I poked around. The functionality is barebones as you can expect. Lots of, "Hello! I'm looking forward to discussing!" without any actual, you know, discussion.
I'm not sure how much online book clubs can really work.
I've poked around and recently tried out
Fable. It's a fair amount better streamlined than the Amazon Book Club functionality, and it sort of works. The service makes $$$ with some premium book clubs you have to pay for as well as purchasing eBooks through them, which allows some functionality on their platform. It works fairly slick, but I haven't really found a groove with it yet.
I don't know. I feel like community on Reddit or even joining a Discord with some like-minded folks feels OK enough for online book club stuff.