Do I need to use Google Tag Manager, or can I use GA4 directly?

Either works, and you can run both at once. Turn on the GTM platform and enter your container ID if you want everything to flow through Tag Manager — the module pushes all ecommerce events to the dataLayer in GA4 Enhanced Ecommerce shape, so any tag you build there receives them. Prefer to skip GTM? Turn on the GA4 platform, enter your Measurement ID, and the module loads gtag.js and sends events to Analytics directly.

Each platform is enabled on its own, so running GTM and GA4 together is fine: many shops use GTM for custom tags and triggers while GA4 direct handles native event tracking. The common mistake is double-counting — if GTM is already firing a GA4 tag from the dataLayer, don't also enable the GA4 direct platform for the same property, or you'll record each event twice. Pick one path to GA4 and keep it.

In the module these are separate adapters with separate required fields: GTM needs a CONTAINER_ID, while GA4 direct needs a MEASUREMENT_ID. The master tracking switch must be enabled first; if tracking is disabled, or if a platform is active but missing its required ID, the front-office scripts for that platform are not injected.

GTM route: enable GTM + CONTAINER_ID = GTM-XXXXXXX; create GA4 tags inside Tag Manager from dataLayer events.
Direct route: enable GA4 + MEASUREMENT_ID = G-XXXXXXXXXX; leave GTM out of the GA4 path.

GA4 direct also has optional settings that GTM does not use in the same way: IP anonymization, user ID tracking for logged-in customers, and an API secret for server-side resend of missed purchases. GTM is better when you want one container to control several vendors; GA4 direct is cleaner when you only want the module to send the standard GA4 ecommerce events without building tags in GTM.

This is part of Marketing Revolution, which unifies tracking for Google, Meta and more from one place.