If the (presumably Vizio) TV is not a Roku TV, then there is nothing the Roku app on a phone can do with it directly.
If you install a Roku streaming device on the TV, then the Roku app on a phone can connect to the Roku and control that, which you then view on the TV.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X