My D6 site is installed in /var/www/vhosts/myname/httpdocs, and I created a downloads directory at /var/www/vhosts/myname/downloads. I've tried everything I can think of to put into the File Paths field at admin/store/settings/products/edit/features to no avail. I would assume the relative path would be ../downloads, yes? I also tried the absolute /var/www/vhosts/myname/downloads, neither of which worked, nor did any mind-boggling combination yet attempted. So far it just continues to give me "is not a valid file or directory".

Please help.
Stuck and frustrated.