In the Partner Centre, click on the event you are checking. There are 3 places you can check to see who has signed up.
1. The 7 Dimensions tab β If someone is on this list, they have joined your group.
2. The Participants tab β Everyone who has been invited to your event, will be on this list. Whether they have joined the group or not yet responded to your invitation is listed under Status.
3. The On-Boarding tab - Everyone who has been invited to your event, will be on this list. You will be able to see exactly where they are on the process: from Invited to Sign-up to Payment to Ready.