Add a supplemental structure to the root node of the item-based model in the workspace area of the Configurator.

A supplemental structure is a set of predefined questions that you can use to guide customers through the configuration process. You can add a supplemental structure to the root node of the item-based model in the workspace area of the Configurator, and then associate it with a dynamic user interface.This way, the Configurator will display the questions to the customers before showing them the list of accessories and parts that match their needs1.

References:

How Supplemental Structures Work in Configurator

How Item-Based Models Work in Configurator