Official comment
By default, your Ontraport order forms will have a set quantity for purchase that you input. You can allow the customers to change the quantity, and in the dialog you can set the "minimum allowed" quantity. So there is never a circumstance where Ontraport is forcing a zero quantity order on you.
Many customers do use a zero quantity for other reasons, such as two products on an order form with the option for the customer to choose which one they want, and which one they don't want (which they adjust to "0").
You can also set a condition for your product delivery that requires the purchase price at a certain level. In the image it is set for greater than or equal to $1.
