This is the newer version of the existing Roku Remote app to support newer Fitbit devices like Versa 3 and Sense. Functionality is the exact same as the original app.
Make sure the install at least version 1.7 of the Find my phone Companion app by Seshu from your play store.
Then you need to do an in-app purchase for the Roku remote feature from the "More Features" button in the companion app and then enter your Roku TV's ip address once its all done.
The in app purchase price for this feature is $1.25
Note: This app only works for android phone users.