I had to call too and they were pretty much clueless and said wait for 48 more hours.
From reading online for a different galaxy tablet, it claims that while you are on the plane you have to simply connect to the plane's gogo wifi. Then open up CHROME (not any other browser), and their system should auto detect that you are a customer who qualifies for the free offer - and it will redirect you to a special login page. This may or MAY NOT be true for our 10.5 Galaxy Tab S tablets. We got two of them last week and will be travelling 4 flights in the next week. Hopefully it works, because no one seems to know.
Getting the other perks (apps) was right in the samsung app mentioned above, but the gogo offer seems to have very little information. Everything is vague about it, and tech support doesn't know either.