Any subscriptions made through third parties like Roku are typically only good on that third party's system.
Because your subscriptions are with Roku, not Acorn and Britbox, these channels' apps probably will not recognize your logins on other systems. Subscriptions obtained through Roku are typically accessed through The Roku Channel.
If you subscribe directly with the channel on its website you can then view the channel on any platform that it supports using your login credentials for that channel.
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.
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