Make sure you have a lot of space left over on your Android to make room for the game as you try to install it. Or were you able to install it already?

Part 2 allows you to see all the content in the game currently. When you start the game up if you have never played the game you can just choose the "Start" button from the main menu screen to begin from the start.

There is no requirement to install the anything before installing version 8. We don't have a game file labeled part 2 on this storefront, only V0.8. If you can install the Demo (Part 1) here you should be able to install the V0.8 one.