Did you go to the Internet link shown on the ATV?
I suggest you do it with an iPhone or iPad in front of the ATV connected TV.
I also suggest you first create an account at PBS before starting the "activation" process.
- Enter the url: pbs.org/account (I didn't take a screenshot, just enter the url, it's very short)
- Enter the code shown just below step 1.
- You should no see a list of PBS stations. Pick the local (or closest?) one.
Now, that's the way it's supposed to go. I had to create an account at PBS, since I did not have one. From there, I was dead in the water. There were no other links available. And I never saw a page to select a PBS station.
I decided to Restart my Mac and my Airport. Returned to the ATV to see it requesting I update it. Still nothing.
To make a long story short, I finally got a "Code Expired" message on the ATV and used my iPad to access the link, eneterd my PBS username/password, selected a station and everything now works.
BTW, you do not have to use FB nor Google+. Just click the 'PBS' icon. Hope that helps! 😉