Quantcast tags are fully supported by Google Tag Manager. In order to proceed, you will need access to your Quantcast tag. Follow the instructions below to add the Quantcast tag via Google Tag Manager.
1. Create a container
Enter the container name, select Web, and click Create.
2. Agree to the Google Tag Manager terms and conditions
3. Place the Google Tag Manager container on your site
You will see a snippet of code once you create the container. Per Google’s instructions, copy the code and place it on every page of your site, immediately after the opening <body> tag. All additional tags will be managed from the Google Tag Manager interface once the container has been added to your site.
4. Create a new tag
5. Click on ‘Custom HTML Tag’ and click ‘Continue’
6. Paste your Quantcast tag in the Configure Tag box
7. Select ‘Fire On’ and ‘All Pages’ and click ‘Create Tag’
8. Publish the tag