If you want to track the page activity by adding pixels to the vouchers page, the best way is to add them to the GTM container and add the GTM tag to the Vouchers Standalone page.
Step 1: Login to your GTM container and copy the first script
Step 2: Log in to aiva Dashboard and click on Connect. Go to the Applications tab.
Step 3: Select Connect to Google Tag Manager.
Step 4: Add the following script followed by your Google Tag Manager script that you copied in Step 1.
<script>
dataLayer = [];
dataLayer.push({});
</script>
<!-- End of GTM dataLayer -->
Sample Script
<script>
dataLayer = [];
dataLayer.push({});
</script>
<!-- End of GTM dataLayer -->
<!-- Google Tag Manager -->
<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-N3SWXXXX');
</script>
You are all set!