MarketPress - Unlimited Downloads to Paid Subscription Members

Hi, I have been trying to work on a way where I can offer free downloads to paying members (with a monthly or yearly subscription). I am trying to use Paid Memberships Pro Plugin and MarketPress to accomplish this. I've tried a couple ways but had no success. I have an idea for trying another way but Im not sure what custom field or variable is suppose to be used.

For example my code so far, which I will place in my single product page -

<?php do_shortcode('[ [membership level=”2?]'.$file_direct_download_link.'[/membership]'); ?>

Any help is appreciated, thanks.