Who said it was free? iTunes charges for it. You either have to subscribe to AMC (which costs money, of course), or download from iTunes.
The only way to watch it for free is to steal it by illegally downloading it.
Another Reason The Walking Dead is big with the 18-49 Crowd is that you can legally download each episode within hours of it being broadcast.
I took your reply to my question in the context of his original assertion.
or streaming - 1channel
I watch “The Walking Dead” through Amazon instant video. $1.99 per episode, and you don’t have to mess with Apple software.