Digital Download - ZenCart - Setup

We have a new store in which we want to offer various Zip files which are provided by our various developers. They are all very busy and have no time to help me. I have installed [login to view URL] I do not know if this is right. I also bought and downloaded this [login to view URL] thinking it would be better, only to find out I have to use Paypal and the IPN which I can't do as it is disabled due to our 9 stores becasue I can't have one call back running 8 stores so Paypal is already being used up on other stuff We also are using a Digital Shop Template. I do not know how to offer a checkout process that allows the buyers to buy these products listed, and be able to be sent a link securely so that they can get their zip file paid for. My vision was like many other wesbsites it to protect the file via a lic or key to access or unlock the file. I also understand it can be achieved via using attributes controller method, and I have no preference as long as it works is secure, and creditable for the product owners to get paid Things are partially set up and just need to finish the aspect to a working model. MUST BE LOW PRICE as we have a budget and need much more work done afterwards. If you are affordable, then you can have the further work. the site in question is [login to view URL]