While there's not a Roblox app for ChromeOS, it's still possible to play using the Android app on some Chromebooks, or by streaming the game.

How to Play Roblox on School Chromebooks Using the Play Store Starting with the easiest, but most unlikely solution is simply downloading Roblox from the Google Play Store. It’s a hit-or-miss ...

The new version, available in the Play Store, offers much higher frame rates and faster load times. You can fly around with your new Chrome-themed jetpack to celebrate.