As specified in the Terms, you must submit "a 3D model, "3D models, materials, tools, applications, etc., that are intended for use in VR space" as your exhibit.
After doing so, you may promote other works or services such as commission in places like product explanation text and store page.
FAQ
Can I advertise commission or other services on the store page instead of exhibiting a product?
While it is permitted to advertise other works, services or other things, you need to prepare an exhibit product such as 3D models, materials, tools, or applications.