To ensure that customers understand how their data will be used, you must provide a link in the Privacy Policy URL field in iTunes if a privacy policy is required by law in your country or if your app does any of the following:

• Accesses user or device data
• Offers an account registration process
• Accesses a user’s existing account
• Uses the HomeKit Framework or HealthKit Framework
• Integrates Apple Pay
• Includes keyboard extensions
• Contains auto-renewable subscriptions or free subscriptions
• Appears in the Kids Category

For more details, read the App Store Review Guidelines.