As @RaviGautam already wrote, the creation of the In-App-Purchase must be sent, as well as connected to the application inside the panel, you can also change the description and select the assembly. This link first describes where to add the in-app purchase in iTunesConnect to the application that you want to use internally.
This must be done before submitting the application. If you defined In-App-Purchases but did not connect them to your application, Apple will reject your application because you must have some application that you installed in the shopping application when creating the App-ID.
Also, changing the description for purchases in the application or something else, it must be sent and viewed by the apple team before the user can use it inside the application.
Here's how to connect IAP to your application on the application details page:

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