The registration settings - Settings >> Registration settings - on your TeamUp dashboard allow you to control when your customers can book/cancel classes, put limits on how many registrations they can make per day and enable waitlists.
The booking and cancellation settings can be global for all offerings, or they can be customised for each class type by creating multiple 'Registration timelines'.
Global registration settings for customers - such as maximum, number of allowed failed payments before their membership is unusable, etc. - are controlled from 'Customer settings'.
The 'Waitlist settings' determine whether a class type has a waitlist, its size, and how long your customers have to accept a spot if they're not eligible to be auto-registered.
From 'Calendar settings' section, you can also edit certain calendar settings, such as whether you want to display your attendee counts, which day of the week it should start on, etc.
For an in-depth look at how each section works, please see the links below.