Support/App Store Connect/Configure in-app purchase settings/Enter server URLs for App Store Server Notifications
Configure in-app purchase settings
Enter server URLs for App Store Server Notifications
App Store Server Notifications provide information about key events related to your in-app purchases, such as changes to a subscription's status or the refund of an in-app purchase. In order to receive these notifications from the App Store, you must provide a URL in App Store Connect that links to your server. You can enter URLs for both production and sandbox endpoints.
If you do not provide a Sandbox URL in App Store Connect, please note that the App Store will automatically send notifications for both environments to the Production URL provided. If you only provide a Sandbox URL, no notifications will be sent in production.
From Apps, select your app.
In the sidebar under General, click App information.
Scroll down to General Information, then go to App Store Server Notifications.
Under Sandbox Server URL, click Set Up URL.
Enter the URL that you've determined for App Store Server Notifications.