How setup coupon to buy 3 items get one free

Hello. I need to set up a coupon code for buy 2, get 1 free. I don't want to set it mandatory as a 2 purchase limit because if people want to purchase just 1, that is fine, they just won't get the deal. They only get the deal if they put 3 in their cart and apply the coupon code and then it will make the 3rd one free. How do I accomplish this?

You can create a coupon code that has a fixed amount applied to the subtotal and only accepts the coupon code based on the minimum amount.

https://www.jotform.com/help/233-how-to-add-coupon-code-to-payment-forms

Please give it a try and let us know how it goes.