Note that these forums provide largely a superset of Slack functionality - real-time notifications, keyboard shortcuts for everything, etc. You might want to consider creating a “chat” topic in your study group category instead. You get many benefits, including proper threaded discussions, no need for folks to register for a separate system, better linking to other topics…
(Having said that, if local study groups want to use slack, they’re welcome to. But note you will be less connected to this community if your discussion is elsewhere).