You can always see the reservations in the waiting list in: Reservations / Waiting list. Here we have 13 waiting list items from which 10 will become valid reservations once the Zapier automation launches at the scheduled time.
Note that the customers (or the customers and the admins) can receive an email notification after their request is added to the waiting list. In order to do this, add a notification for the added to waiting list event on the Notifications page.