In order to unlock the help panel for Storage, you have to:
- Hit your storage limit (earn more of a resource that you can actually store), this will bring up a notification for the Storage help
- Tap on the notification: its content should be displayed, the panel should add to the list, you should earn the achievement, ...
It looks unusual not to have hit storage limit after such play time, so it might be a bug. If you suspect so, please send us your saved game via in-game email or by connecting to the Spooky Universe.