Let’s play with the figure maximum number of particiapnts: one person. When the event has reached its maximum number of participants (one person) the registration page will automatically be closed. But it is only when you have processed the registration, that it counted in the maximum number. If three registrations are made, and non of them are processed, the registration page will remain open and people can still sign up. That is, the registrations must be processed to be count against the maximum number of registrations.