Make an item downloadable after purchase

Hi I am making a website that sells templates for a script and after serching and serching for a templates script I setled for a stor instead and for zencart.

what I would like to know is, is there any mods or anything that I can put on zencart so that when someone purchases somthing and after they pay they get sent back to a page in zencart to download the template they just purchased.

hope I explaned this ok

https://www.zen-cart.com/tutorials/index.php?article=71

Thanks I seen that and followed it but I dont get how it works.

if I make it a dropdown called download with yes and no options then add it to the product it ads the download file to both options yes and no, if I make it a radio button its always selected.

can someone please explan better how this is done.

Idealy I would like the following things on the product page, first off a dropdown named downloads with options yes and no, when yes is selected and they pay they can download, when no is selected and pay they canot download. another option would be EMAIL so the customer puts his/her email in and the item gets emailed to them. all of those options would be under the heading "choose your receive options"

basicaly I want them to be either able to download after paying or enter an email address to have it sent to.
thanks