This script was used for LearnMean.com to proccess payments from paypal then serve a zip folder to the user, and then add them to the blocked.csv file so they wont be able to download the file more then once.
The $SECRETKEY is stored when you create a paypal button
The $FILELOCATION is where the file you want to serve is located on the server.
If you want to use pretty urls configure your server to use the .htaccess provided.