Back in the day, I created a group called Dachshund Lovers on Facebook. It was open just to people at my university, and it gathered a few members but wasn’t anything big. Then later, when I was able to open it up beyond my university, I made it a public group so anyone could join. Things were fine, people joined and I didn’t have to do anything about it. Just anyone who wanted in could join and there was no approval process.