It sounds like the content is being metered in your app. The collection in which the articles appear has a Product ID associated with it. When you edit this Product ID in the Products & Subscriptions Dashboard, is it set to Entitled or Restricted? If you set the collection's Product ID to Free, all articles within that collection will be available. If you don't want that collection to be free--if you want to require a purchase or sign-in--then you should edit article properties and change the Article Access from "Metered" or "Protected" to "Free." Publish and check again.