Can someone join an Event?

I have been searching and searching, but not found a way or a button where a member can join an event.

In my profile, I can edit the event and I can see that there is a tab that shows the Attendees, but how do the attendees get in there in the first place? I have been using two different users, myself (admin) and a fictional one (subscriber) to test things with, in two different browsers.

Can anyone help?

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