When you have the Scheduler you have the ability to control the number of units a user can select overall as well the ability to allow users to checkin. To begin, make sure you are in the Scheduler interface by selecting the “Schedule” under the "Settings" menu.
Next, click on “Actions” and select “General Settings.
To limit the number of units a user can select click the “On” and enter the number of units a user can select.
To allow “Checkin” and/or “Checkout” click “On” below their title. For Checkin you can enter how many minutes before/after a user can checkin from the start date and for checkout users will automatically be checked out at the end of the session.