Google Tag Manager
Integrating Google Tag Manager into your Storefront
Navigate:
Main Menu → Storefronts → Choose Storefront Host → (Storefronts menu) Privacy & Tracking → Google (tab) → Scroll down to 'Tag Manager section
You need to configure the following credentials:
Container ID (Required)
Install a container in your content. Near the top of the window, find your container ID, formatted as "GTM-XXXXXX". Click your container ID to launch the Install Tag Manager box. Copy and paste the code snippets into your website as instructed, or download and install the appropriate mobile SDK.Setup and installation - Tag Manager Help - Google Help
https://support.google.com/tagmanager/answer/6103696?hl=en
Try using this chrome plugin for testing the google tag manager:
You may receive a warning that the script is not rendering in the head section of the page. Please note that the script is still functional. Please allow up to 24 hours after configuring your container ID for google to begin registering the traffic.
Server Side Script URL (Optional)
Opt in to (recommended)
These settings allow you to comply with General Data Protection Regulation (GDPR). For more regarding CGPR see:General Data Protection Regulation (GDPR)
*Disclaimer: This is not legal advice. The General Data Protection Regulation is complex and each merchant should obtain legal advice to discover how the regulation applies to their specific business.
Google Troubleshooting tool
https://tagassistant.google.com/ . https://support.google.com/tagassistant/answer/10039345#zippy=%2Cin-this-article