When logging into Google Tag Manager for the first time, what needs to be set up?

When logging into Google Tag Manager for the first time, you must set up a Tag Manager account. This is the foundational step that allows you to create containers, manage tags, and publish changes. Without a Tag Manager account, you cannot access or utilize the platform. A Google Analytics account is a separate product that you might integrate with Tag Manager later, but it's not the initial setup requirement for Tag Manager itself. The data layer is an advanced concept for passing data to Tag Manager, and cross-domain tracking is a specific configuration, both of which are implemented within an existing Tag Manager account and container, not during the initial login.