Remember that there are two transactions for every Printful order:
- Your customer pays you for the order
- Printful charges you for fulfillment
What's left in between is your profit.
It's up to you to set up a method for customers to pay you on your store. You should set up a third-party payment processor. Check out options like PayPal, Braintree, or Authorize.net. If you have a Shopify store, you can use the Shopify payment processing solution. Or if you have a Squarespace store, you can visit their Help Center to learn how to connect to a payment processor.