Drupal

Add the tag to every page of a Drupal site, in your theme’s template.

Put the tag in your theme’s html.html.twig, just before </head>. Use a theme of your own, or a subtheme of the one you use, so that updating Drupal or the theme doesn’t remove it: copy html.html.twig from the base theme, such as core/themes/olivero/templates/layout/, into your theme’s templates folder, and add the tag to your copy.

<script async data-domain="example.com" src="https://fiveb.ar/js/tally.js"></script>

Then clear the cache, under Configuration, then Performance, or with drush cr, so Drupal uses your copy. See Drupal’s guide to Twig templates.

Once it’s live, check it works.