Okay I think I'm starting to understand what you're trying to do. The way you have it structured you're passing download as a variable to the link method. What you want to do is create a urls that calls the page/action/id method. So it should be
<a href="{$Top.Link}/download/{$SongFile.ID}" title="$Title.XML">Download</a>
so the url is structured: url of page / method you want to call / id you want to pass
Hope that helps