When you first access the app, you need to choose a country. For ease of use choose your subscribing country. You can easily change countries later on via the Menu button.
The main app interface has three buttons at the bottom. Choose User Account and click the Login button to log in.
After you have logged in once, you can access member content across all editions without having to log in again.
If the User Account tab shows the green Subscription active banner, you can access member content but you will need to log in to access My Account or Subscription information. Click Membership Log in to proceed.