An adult creates an account for the app at https://account.carrotkitchen.com/, or directly in the app. After subscribing, you can create a child profile for the service in the app.
Once the app has been downloaded from the App Store or Google Play to a mobile device that the child can use, the first sign-in will be with the parent ID, after which the child’s profile is created in the app. The child can then use the app directly with their own profile.