If you are downloading a streaming media player to watch the show, only download apps directly from the Apple App Store, Google Play Store, or official television operating system storefronts.
If your goal is to download Episode 1 so you can watch it without an internet connection (on a plane, train, or remote area), you can use the official download features built into the streaming apps. This is the only safe way to "install" the video file onto your device. On Mobile Devices (iOS & Android) cunk on earth episode 1 install
This guide will explain exactly how to set up both so you can start watching. If you are downloading a streaming media player