Why am a i getting a message saying "ERROR NO AUTHZ" on the History Channel app?

Please identify your ATV version and software version.

Is History Channel included in your cable package?

You might check on their website, since it's their app.

Unless you are paying for a History Channel subscription through a cable package they will not allow you to view content through an app.

HIstory Channel and other channels get money to make programs from advertisers and cable subscribers.