Trigger an Event (Conversion) in Google Analytics (GA) based on Custom Event

Create 4 Data Layer variables 
 eventAction 
 eventValue 
 eventCategory 
 eventLabel 
 Here is one example, repeat this for all the variables above. 
 
 Configure your Event in GTM 
 Create your conversion event tag and use the above variables to autofill your event as shown in the image. 
 
 Set event based trigger 
 As shown below. We used "new_subscriber" as event name, you can use anything you want. 
 
 Add the trigger to your page (Method 1) 
 Add the following dataLayer code ABOVE your GTM script on your thank you page. 
 <script>
 window.dataLayer = window.dataLayer || [];
</script>
<script>
 // dataLayer.push({'amount': 11})
 window.dataLayer.push({
 'event': 'new_subscriber',
 'eventCategory': 'testcat2',
 'eventAction': 'myaction2',
 'eventLabel': 'mylabel2',
 'eventValue': 23,
 });

</script>
<script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
 new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
 j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
 'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
})(window,document,'script','dataLayer','GTM-XXXXX');</script>
 
 Add the trigger to your page (Method 2) 
 If you want to trigger this event with a button click. 
 You can use the following code. 
 <button onclick="window.dataLayer.push({
 'event': 'new_subscriber',
 'eventCategory': 'testcat2',
 'eventAction': 'myaction2',
 'eventLabel': 'mylabel2',
 'eventValue': 23,
 });">Signup</button>
 
 After you implemented, trigger the event on your page and head to GA to see the data in action. 
 
 The UTM will be associated with your event as well 
 
 Or you can see it under Behavior > Events > Top Events (this may take longer to show up after your test)