I just bought the Sims 4 to download it on my chromebook but it will not let me download. Help!!!?

Just to add to what Cantra said:

If you bought it directly from Origin you should be able to refund it within 7 days of purchase (or 24 hours after you first launch the game which obviously you haven't been able to do). Unfortunately if you bought it from elsewhere it's unlikely you'll be able to refund, you'd have to ask those you bought it from.

Or you can just keep it for when you do have a Windows or Mac computer.

If you want a refund you go to the request a refund page below, log in to the account you bought the game on and if a game is eligible for refund it will show there and you can request a refund.

https://help.ea.com/en/refund/

You need something running either Windows or the MacOS operating systems. A Chromebook doesn't use either, it's basically just a Chrome browser. It lacks the libraries of instructions and functions that a Windows/Mac game is expecting to find within the operating system.