It looks like you are now getting into the die statement. You should try commenting out the die line by adding a // in front of it. When you do this it should then attempt to trigger the download, please give this a try and post back with your result.
The fact that you are now getting into the die statement shows that the trigger 'same page post' does not work for you as intended on your server. This is likely an issue with the referer server value, if this is not set correctly this trigger will not work for you. Instead you have manually updated it to be any page post.