Google Tag Manager scripts can be added to your Landing Page.
The option to add this information can be found both within the Builder as well as in the Dashboard.
NOTE - Follow the link to learn How to get your Google Tag Manager Script
How to add Google Tag Manager script on the builder:
Navigate to Global Settings Panel > Tracking Codes.
Add the Head and Body scripts in the respective provisions.
Then, save your changes and publish the page.
How to add Google Tag Manager script on the dashboard:
Navigate to the tab Settings > Tracking Codes > Other Scripts within the respective landing page.
Add the Head and Body scripts in the respective provisions.
Then, save your changes and publish the page. That is all.