When you make a booking online via the official Spaceships booking website - to get the lowest price available and secure the best deal - you'll receive a payment & booking confirmation on screen. You'll also receive a payment & booking confirmation via email.
When you pay the remaining balance via the secure Spaceships payment system, you'll receive an on screen confirmation as well. And when you log in again, you'll see that the payment has been processed.
When logging into the Online Check-in Portal, you can also check the balance of your booking. And while you are logged into the check-in portal you can fill in the remaining details and/or update your booking. This must be done & dusted 72 hours before the scheduled day of pick-up.