[Plugin: Easy Digital Downloads] File size limit issue on downloads

I recently purchase the Stripe and Mailchimp addons, and tested my first download successfully. Then, my second seemed to work except that after clicking on the download link, the file downloaded at zero bytes. Through trial and error, I found that there seems to be a file size limit for the downloads. I found that if the download is 6mb or under, it works perfectly. Anything larger, and the download is corrupt with zero to a few hundred bytes in file size. Most of the downloads that I planned to sell through this plugin are sets of mp3’s which are 20-40mb each. What can I do to fix this issue? I just installed the plugin and extensions with the latest versions, on WordPress 3.4.

http://wordpress.org/extend/plugins/easy-digital-downloads/