Hey @Lilruss942012
Welcome to the Roku Community!
You're seeing this error message because you have an existing subscription for that channel billed by Roku. Just a heads up, there are two options to sign in to the Shudder app: The Shudder and the "Shudder on Roku channel." I highly suggest signing in to one of the apps using your login credentials.
To check if a subscription is billed and managed through Roku, visit my.roku.com/subscriptions and click on My Subscriptions.
If you need any further assistance, just let us know.
Best,
The Roku Community Team
Rhea V.
Roku Community Moderator