Jojojo
As far as I'm concerned, it doesn't support full features like ability to make comments or posts. For creating persistent subscription and settings, it basically stores them in a special URL, which Redlib expects you to add to your bookmark.
To add subscription, go to subreddits you want to subscribe to, then click on Subscribe. These subscriptions are essentially stored in your browser. To export the current state (subscriptions, settings, etc), go to settings (https://r.genit.al/settings), and scroll down. Right click on the text "this link" and save it. Using that link restores your current state.
It generates a link that looks like this:
https://r.genit.al/settings/restore/?theme=system&front_page=default&layout=card&wide=off&post_sort=hot&comment_sort=confidence&show_nsfw=off&use_hls=off&hide_hls_notification=off&hide_awards=off&fixed_navbar=on&subscriptions=factorio&filters=