When you create your account the standard check-out workflow is enabled, when you go to check-out a booking no matter what booking type it is, the system will look to see the following the customer has any other bookings either due to checkout or that has checked out and has and outstanding balance.
If so the following screen will appear, and you can add all of the customers outstanding bookings onto the one invoice for payment/checkout. Once you have clicked the various bookings click on the Checkout Bookings button to proceed.
On the main checkout screen you can then add a payment for the booking(s) and checkout the bookings or your can click the Leave Unpaid toggle to checkout the bookings but leave them as unpaid.
Once checked out the system will email the customer their PDF receipt. If you have the Stripe payments feature enabled, on the screen you will also have the ability to charge their saved card, add the details of another card, or if you have the Payment Terminal set up you can send the amount due to the terminal for payment.