There are three key components to consider when building a Super App:
The Super App has to connect with the Mini App Center through its API to get the list of approved Mini Apps, and expose them to the user in their UI.
It probably exposes some services (API) to their Mini Apps, for example, Pay(), GetUserId(). Those services need to be implemented within the Super App.
The Super App (app itself) would be deployed in each store (Google Play, Apple Store).
The Mini App will be uploaded to the Mini App Center, and upon approval from the Super App owner, it will be visible in the Super App, based on the design and discovery criteria.
Each App has its own backend server.
The Super App accesses the Mini App Center to obtain the list of available Mini Apps and present them to the user in the Super App UI, according to the implemented search and discovery criteria.
When the user selects a Mini App, their metadata is downloaded from the Mini App Center and the app is executed within the context of the Super App. The user begins to navigate through the Mini App, which he could eventually invoke to resources/services of the Super App.