[Request] Adding other fields along with your post fields

I have a custom post type that holds products from the website and I made a Custom form where people can order these products through e-mail.

What I’d like to add is a quantity field for each of my post types, so someone ordering can also request the quantity for each product. Is such a thing possible with this plugin currently ? I guess it isn’t, right ?
Messing around with the plugin, I was able to add the field, but I can’t find a way for that field to be captured. Think something like that would also enable a lot of other creative uses of this plugin.