Submitting In-App Purchase for the first time little confusing. You have to include IAP while submitting the binary. But this option will not appear always. It will appear when you create both In-App Purchase products and include them in the app. Here is the details guide: Implement In-App Purchases in iOS Using SwiftUI.
After submitting the app, you may get this message from the reviewer:
In-app purchase products associated with the app version submitted for review, such as , could not be found in the submitted binary.
Here is the workaround:
First, you have to create an in-app purchase product:
Go to App Store Connect > My Apps > Your App > In-App Purchases.
Fill in all the required fields. DO NOT SUBMIT. Left it as it is. Make sure the status of your IAP products is “Ready to Submit”.
Come in the Xcode. Create a .storekit file. File > New File From template. Select the StoreKit Configuration file.
Here, check Sync this file with an app in App Store Connect. Select your team and app.
Now, you should able to sync In-App Purchase product you have created in the app store.
After implementing the in-app purchase code, upload the binary. In the app store connect, you will able to see an option to select an In-App Purchase. If you do not see this step, try to figure out why. If you are not able to select the In-App Purchase product when submitting the app for review, it will be rejected. So make sure you are able to select in-app purchase product first.