Chromebooks are able to buy access to certain paid-access games, but are unable to actually play them afterwards. This is presumably because they are categorized in a different platform between the website and in-game client.
For our game, we have received a couple of complaints of users who purchased the game while on a Chromebook, yet were not able to play it afterwards.
It seems like a Chromebook falls under a mobile device and our settings are only checked for Computer compatibility. I don’t believe those who are on a Chromebook should be able to purchase a game they would not be able to play.