Basically There are 4 Steps you need to follow (they're all part of the onboarding flow):
Create an Organization.
Link your Google Account with Dockup (Obligatory Note: You should have google account. And you should have agreed to Terms & Conditions in GCP console--They'll ask for this when you log in to GCP console for the first time.)
Enable Billing Account in GCP Console. This'll take few mintues. So have patience. Now create a cluster.
Create a Blueprint.
Don't worry, you'll be guided through each of these steps when you sign up.