it's the The Omnibus Collector's™ Comic Swap and Community and yeah you need to be accepted. If they don't accept you just message a mod, they might think you have a fake profile or just haven't got around accepting you yet.
it's not cbr related it's created by a guy called Ryley Moore who has a website called The omnibus collector. But it's a very active and friendly group. Only downside is that it has so many members there are a lot of redundant posts but that's unavoidable probably.