As noted from Live Support with James Morris
When enabling the RSVP with email address add-on, which allows RSVP using email address instead of requiring registration, once the user RSVPs, the user is still created in WordPress.
Slso when I look at who's RSVP, i get a sorta 404 error, is that because there's another addon that wasn't turned on or a setting that needs to be adjusted. This is what it was saying.
It seems we can’t find what you’re looking for. Perhaps searching can help.