A booking in MakePlans ends up in the calendar of a resource. By default the capacity on a resource is 1 so there is only 1 booking for 1 person at a specific timeslot. But this can be adjusted to allow multiple bookings or multiple people pr booking within the same specific timeslot.
To allow multiple bookings pr timeslot set capacity to be more than 1. Let's say you want to have 5 simulations bookings pr timeslot then set capacity to 5.
Number of people pr booking is controlled by the service. So if you want to have max 4 people pr booking set 'Max nr of people pr reservation' to 4 on the service. So if you have set 4 as capacity then the resource if fully booked with a booking for 4. If however you set capacity to 20 you can have 5 bookings with 4 people each (or 20 individual bookings) before the resource is fully booked.
For a resource with capacity 5, the resource will be fully booked when either there are 5 bookings or bookings with multiple people that adds up to 5 (for example one booking for 2 people and one booking for 3 people).