Hi We only support Firefox on the platforms for which it is designed: Linux, Windows, MacOS, Android (Google Play), iOS and Amazon Fire TV. We do not support installation on Roku. If you have Firefox for Andriod installed on an Android device, this [https://support.mozilla.org/en-US/kb/use-firefox-android-send-videos-your-roku article] will walk you through how to cast to a Roku device.