403 Forbidden error

Hi, I add a PDF ebook on the downloads, i can download it after the purchase directly from the link on my site, but i can’t download it from the email i receive after the purchase. It give me this error:

Forbidden

You don’t have permission to access this resource.

Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request.

The page I need help with: [log in to see the link]