Register for free here: https://www.quantcast.com/gdpr/consent-management-solution/
You will receive an email to activate your account.
Once your account is activated, log into Quantcast's consent management system.
If you’re not already in the Sites section, click on Privacy at the top of the page.
Click on “Protect a site” and follow the Quantcast instructions to add your site's domain to the dashboard. Remember to add support for the additional Vendors suggested by Google to maximize revenue.
You can add more than one site here. You should see them in the chart.
At this point, just click on "Universal tag" in the top right, copy the code, and paste it in the header of your site.
If you have Wordpress, you must install the Quantcast choice plugin and paste the universal tag into the plugin's Settings page.