Hey,
This is a fully custom made store. Very difficult so I cannot give you any guidance but you can build a customized checkout section with the createOrder() API with your Wix stores, but again this will also require some experience to build.
Explore the Examples section if you are beginner but keep in mind you won’t have a full walkthrough on how to build something this complex.
Also note that using the createOrder() API the sales data will not be shown in the Sales Analytics section of Wix Stores so no reports if you use the API (I know I know)