In-app products in Deepwall represent the in-app products (subscriptions or one-time purchases) that users purchase on mobile platforms (App Store, Google Play Store or Huawei AppGallery) via your mobile app.
So you need to setup your in-app products for your iOS apps on the App Store Connect first before registering them to Deepwall.
You can check out the following guide to learn more about setting up in-app products on App Store Connect.
Server to Server Notifications is a service that Apple provides for auto-renewable subscription products. Even though Deepwall does not require server notifications from the App Store and can regularly collect subscription information from App Store, sending server notifications to Deepwall will speed up webhooks and minimize lagging for analytics.
For Apple Server to Server Notifications, the URL provided in the Deepwall panel must be set in App Store Connect.
You can check out the following guide to learn more about configuring server-to-server notifications: