Download PDF file Option in Zen Cart

Hello, I want to put download option for pdf file in my zen cart website. I can download .zip or .pdf file with option name and value at the end of check out but I want to put download option on product info page and before shopping cart page. This is very simple job who are expert in zen cart. I have already made download option on product page but I am not able to download seperate pdf file per product as Its showing common downloadable file for all products. customer must download file after login in website. noone can download file without login. I want to finish this work today. so if you are able to do it today then you can bid on my simple jobwork. Thanks