If you are not seeing the download button after clicking the link in the email there could be a couple of causes.
1) Make sure you have put the correct shortcode on the landing page. It should be:
2) Watch the url after you click the link. If you see that the link is being striped of the verification number this is caused by either another plugin such as YOAST Seo, a security plugin or your htaccess file which was altered by the security plugin. Contact your Website Administrator to correct this problem.
( Example: ?ver=3ee55762e12f408aeedfdc4fc0e302e9a85b7718 )
3) If you are using YOAST SEO, in the permalink settings, uncheck Remove the
?replytocom variables. and Redirect ugly URL's to clean permalinks.