Do this for the snippet and make the resource-microflow return the currentuser:
Mind you: the MasterPageTracker is being replaced by their new version: GA4. This is not (yet) implemented in the Google Analytic-marketplace-widget. What you need to do for the GA4 variant is to open your project’s directory, open theme/index.html and add this to the head:
<!-- Global site tag (gtag.js) - Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-Youraccount"></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag() { dataLayer.push(arguments); }
gtag('js', new Date());
gtag('config', 'G-Youraccount');
</script>
and of course replace G-Youraccount with youraccount. Now you are ready for the next decade :-)
In order to add the MasterPageTracker to a layout, you have to create a Snippet that contains a dataview with the MasterPageTracker inside. Afterwards you can add the Snippet to the Layout.