Get a Google Tag Manager ID
To use the tag manager, you can create an account and create a container here.
Specify the domain of the site you want to link with the container and select "Web" as the type.
After creating the container, you will see a screen like this. Copy the ID of the form "GTM-XXXX" in this code.
Collaborate with STUDIO projects
Once you have obtained your ID, go to the project dashboard screen of the STUDIO site and click Open the Apps tab. (You will need to upgrade to the BASIC plan or higher to use Apps.)
Click "Edit" in the Google Tag Manager and you'll see the Google Tag Manager ID entry screen. Enter the GTM ID that you have copied and save it. (Please note that if there are extra spaces it won't allow for proper integration.)
After setting up your ID, please do not forget to "Update".
Now you have completed the integration.
※ For more information on how to use Google Tag Manager, please refer to official Google support or external articles.
How to verify that the system is functioning properly
In Google Tag Manager workspace, next to the publish button, you can use the "Preview" button to verify that the tags are embedded and working. After clicking on "Preview", and reload the page in the connected site and if the panel appears such as below, you have successfully integrated with the tag manager.
If the verification panel does not appear, you may have entered the wrong ID, or the integration may not be working due to a browser extension such as Adblock.