A few points of explanation about the Shudder Amazon Prime channel:
The Shudder Amazon Prime Video channel is a completely separate subscription and is not managed through our system
The Amazon Prime Video Shudder channel operates independently of our Shudder App for FireTV
This kind of Amazon-managed account cannot be combined, carried over, switched back and forth, or used on the Shudder website
If you run into any issues with streaming or with your billing, you'll need to reach out to their support team for help.