I've subscribed to the app via the App Store (Apple or Google Play) but can't get into my account?
Have you clicked into the app and used the "Sign Up" and completed the "Tell me a bit about you" section? This is the final part of the registration process before you can access your account - so it must be completed.
Once you're subscribed and have paid through the app store, you can add your personal details and goals through the "Sign Up" section to fully register your profile.