Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
If you are talking about the British/French "War of the Worlds" on Epix, there is only one season of 8 episodes. It just ended a week ago. According to a note in the Wikipedia article for the show, they are working on a second season.
To add: If you liked the 1953 movie version of "War of the Worlds" (the one with the green-tipped triangular ships and the gooseneck heatray), H&I Network is airing a 1988-1990 TV series that was a continuation of it. It airs Sunday nights at 7PM ET. H&I is a broadcast network. No Roku app and even it there was, it would mostly just be a live feed and schedule. Not sure if the series is available on any streaming service.