Once you install the plugin, you will get the option to choose one of the page builders:
Checkout Builder Interface varies by the page builder that you have selected.
Interface of Checkout Builder for Gutenberg Checkou
Once you add or edit the elements, you get the setting Position. You have to select one of the available predefined sections of the Checkout Block of WooCommerce where the element should be displayed:
Available Positions are:
Contact Information
Billing Adress
Shipping Adress
Shipping Methods
You can modify the WooCommerce Checkout Block preferences by clicking the Edit Checkout Page button:
This checkout block is fully controlled and maintained by WooCommerce. For more information kindly check out the official documentation.