Google Analytics Tracking

We have just started to use this plug in. We have not rolled a landing page out live yet because we want to be able to track clicks on the landing page. My question is how do I go about installing a GTM Container tag on a landing page created with this plug-in. To track on a wordpress site normally all you need to do is put the snippet in the header.php of the site but when I go to preview mode nothing shows on the landing page. Any help would be appreciated.