Please try rebooting the app:
1. Log out of your Edoki Academy account (if you were logged in)
2. Open the App Store on your device and check that you are logged in to the account that is paying the subscription.
3. Double-click on the device's Home button, swipe the app towards the top of the screen and then double-click on the Home button again.
4. Reopen the app, the content should start downloading.