WE tv requires authentication against a TV provider. That means cable, satellite, or streaming service. Not all apps accept all services, though this isn't as common as it once was.
The cheapest streaming service that carries WE tv is Philo, which is $25/month. Their package carries just over 60 channels.
If this seems the way to go, and if it allows you to authenticate, you could use the WE tv app. Or just watch via the Philo app, which would act as a "streaming cable" service.
Roku Community Streaming Expert
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