2) create a dynamic site (using Dreamweaver) with test server (I have MAMP installed on my Mac) 
Or is there a 3rd better way to do this?
the 3rd, better way to do this is to convert the existing site in dreamweaver to be a dynamic site that uses your local mamp server for testing.
only the page that will have the download button on it needs to be a php page, all of the other pages can remain as html pages. really all you need to is change the extension of the existing html page that will have the download button added to .php:
change:
pagename.htm
to:
pagename.php
and you're good to go.
