You should extract the zip file on your local computer and upload the includes folder from the template to the root directory of your store, not the /templates folder.

Zencart builds that dropdown in admin by looking for a template_info.php file in includes/templates/WHATEVER_TEMPLATE_NAME.

All the templates on that site should work with 1.5.0, which is more than can be said about templates from Template Monster or Algozone.