most of those groups are on facebook, but quite a lot are on Reddit aswell. The key is to not use said groups to try and self promote, but rather to ask questions and share experiences and insight into the youtube journey. I know Nick Nimmin, Brian G and I believe Derral Eves all have facebook YouTube groups, though I'm not a fan of Facebook.
Nick Nimmin also has a reddit called r/ytcreators or something like that. Google will guide you towards some of them, but I trust Nick Nimmin's and Brian G Johnston's Tube Ritual group to not lead folks down the wrong path. But there are plenty of others.