First of all, you don’t need to use separate custom post type to add your download, using only download manage you can create page like that, also you can easily generate template like the image in previous post using simple template tags in download manager, Template docs:
Templates
However, if you still want to use only download button from wpdm pro, what you need to do is, create a link template only using tag: [download_link] and use this add-on for button style:
WPDM Image Button
Finally use the new template id with your short-code.
