How to hide the quantity until checkmark is clicked?

On the checkout/payment page, I would like to hide all of the quantity fields until a checkmark is selected.

Unfortunately, it's not possible in the payment field. We have a conditional logic that can show/hide fields, but there's no way you can apply in the quantity since the product items belong to a single field. 

Please do not hesitate to get back to us if you need further assistance.