How to match Plans&Pricing checkout behavior with Corvid API?

When I use the Plans&Pricing app out of the box to subscribe to a monthly membership, it initiates a checkout that automatically includes the email address that I’ve logged in with (since I’m already have an account).

However, when I start a purchase using wixPaidPlans.purchasePlan, it initiates a checkout that first asks for all the ID fields as if I wasn’t logged in at all.

How do I match the behavior I get with the out of the box Plans&Pricing with the Corvid API?