Aaaah, if you only have a Chromebook, it was a bit pointless to buy it since you cannot launch ".exe" files on Chromebooks.
To play it on Chromebook, you need to download it on the Google Play Store.
But since you bought it, I recommend you to play the game on Windows, or Mac/Linux (use Wine for those OSes). The game is optimized for PC, with keyboard controls and such.
The game on the Google Play Store is optimized for mobile, so you might have some troubles to play it with your Chromebook.