Hey there Roaks,
It sounds like you are unable to sign into your NHL live account. I would start by restarting your Apple TV with this article:
Apple TV: How to restart your Apple TV - Apple Support
If that does not resolve the issue, you can try restoring the device with iTunes:
Apple TV (2nd and 3rd generation): Restoring your Apple TV - Apple Support
If the issue persists, I would next reach out to support for your account:
Contact Apple TV content providers - Apple Support
Thank you for using Apple Support Communities.
Cheers,
Sterling