Open the Billing & plan page
In the side menu, choose Billing & plan. In the For invoices group, below the list of invoices, there's a Photo sales row with the Connect payout account button.

Fill in the Stripe form
The button takes you to a Stripe form. Stripe, not Picvelo, collects the details needed for payouts: identity confirmation, address and bank account number. We don't see these details and don't store them.
Wait for verification
After you fill in the form, you come back to the panel. Stripe needs a moment to check your details and sometimes asks for an extra document.
Check that the account is ready
When Stripe finishes verification, the Photo sales row on the Billing & plan page shows Payout account connected with a check mark. From then on, your client pays by card when confirming their selection, and you don't have to confirm anything by hand.