Download Products: Proper Setup

Add the product in the admin, then go to Attributes and add a download attribute.
Make sure /catalog/pub is 777 and /catalog/download is 755 and these files in catalog/includes/configure.php have the forward slash:
 
define('DIR_FS_DOWNLOAD', DIR_FS_CATALOG . 'download/');
define('DIR_FS_DOWNLOAD_PUBLIC', DIR_FS_CATALOG . 'pub/');