Working fine now. $_GET variable was resetting in your server when download link was like http://www.estrela.com.br/download/test/?wpdmdl=x, I’ve changed it to http://www.estrela.com.br/?wpdmdl=x, by replacing $permalink = get_permalink($ID); with $permalink = home_url();, in file libs/class.Package.php in function getDownloadURL.