Go to Digishop page, then settings.
  We need to find out path to our file directory.
  And to do that, lets go to system information page
  Take a look at root path. Yours will be different then mine.
  What I want to do is create publically non-accessible secure directory. 
  In my case anything above public_html is public, while below is private,
  and thats where I want to store my files. 
  So I will create an new folder in W:\ , and call it FILES.
  Back to Digishop configuration, and enter new path.
  Make sure the folder name is case sensitive.
  And thats all to it. 
  Now your files will be secure and out of reach from illegal downloading.