I had the same problem. Downloaded file size is 0.
I modified direct_download.php as follows and my problem was solved.
<?php
if( !isset($_GET[‘file’]) || empty($_GET[‘file’]) )
exit(‘Access denied!’);
$file = $_GET[‘file’];
header(“Content-type: application/x-file-to-save”);
header(“Content-Disposition: attachment; filename=”.basename($file));
readfile($file);
exit;
?>