AppleTV Shudder Channel not login

• Subscriptions started inside the Apple TV app have to be viewed inside the Apple TV app. Subscriptions to Apple TV app Channels aren’t valid outside the Apple TV app. Access is granted based on the recognized subscription on your Apple ID account. No manual sign-in applies.
• Access to third party streaming services in their own separate app on iPhone/iPad/Apple TV box, started in-app on such Apple device, requires a different type of subscription, and requires viewing in that app on an Apple device. Access is granted based on the recognized subscription on your Apple ID account. No manual sign-in applies.
• Access to third party streaming services when subscribed directly with them, is the only way to sign in with credentials in their own separate app (or on the web), on any brand device.

These subscriptions are not exchangeable, as they have different terms and conditions, different perks and limitations. Choose a subscription type that best suits your viewing habits, and stick with that.

Apple TV Channels FAQ: Services, pricing, availability, and everything else you need to know - Macworld

Subscribe to Apple TV channels in the Apple TV app - Apple Support

See your subscriptions overview - Apple

Possibly you tried to access an episode that isn’t available yet. Check other sources for the official release date (and time) of the episode. The Apple TV app may have been fed incorrect data about availability in the connected app, causing this fruitless runaround.

If the episode is confirmed to have been released for streaming, but isn’t available in the Apple TV app Channel, then contact Apple Support about that.