Cloudflare Zaraz

Add the tag through Cloudflare Zaraz, as a Custom HTML tool.

Not every tag manager keeps a script tag’s attributes as you wrote them (Google Tag Manager strips the data- ones), so add the tag with a few lines of script instead, with your domain in place of example.com:

<script>
(function () {
  var tag = document.createElement('script');
  tag.async = true;
  tag.setAttribute('data-domain', 'example.com');
  tag.src = 'https://fiveb.ar/js/tally.js';
  document.head.appendChild(tag);
})();
</script>

In the Cloudflare dashboard, go to Tag setup, then Third-party tools, and add a Custom HTML tool. Paste the script as its HTML, keep the Pageview trigger it fires on, and save. See Cloudflare’s help on adding a tool.

Once it’s live, check it works.