Why can’t I get Disney on my Apple TV 3rd generation?

Does Disney+ support Apple TV? - Disney+ Help Center

Disney+ supports Apple TV HD and Apple TV 4K running tvOS 11.0 and later.

Can I use AirPlay to watch Disney+? - Disney+ Help Center

You can still AirPlay stream from an iOS device to an Apple TV (3rd generation).

appletv 3g does not have an app store for users to app add apps

disney+ is an app