Did the giveaway end already? The page says the game is on sale, not that it's available for free.
Bad news. :(
Dear Humble Store customer,
Recently, you were able to pick up a free key for Fractured Lands from the Humble Store. We're very sorry, but this was actually a mistake due to some technical problems on our end.
If you received a key while Fractured Lands was set at a 100% discount, you'll still be able to play the game until 1 p.m. Pacific time on Sunday, November 11, 2018. At that time, the key will be revoked and you'll no longer be able to access the game.
Fractured Lands will be on sale for 30% off from now until 10 a.m. PT on November 17, in case you would like to purchase it after all. We're very sorry that we weren't able to fulfill the 100% discount for you. Thank you for being the awesome customer that you are!
The Humble Store Team
They still claim to be out of keys. Maybe I just missed the point where they restocked but I have a feeling they aren't actually going to giveaway any more keys and are just claiming to be out of keys. The same thing happened with the end of summer sale when you could claim a reward but if you didn't also immediately redeem the key they would just tell you to come back later they they get more keys except they didn't and eventually the redeem time limit run out.
Honestly HB seems to have really gone downhill after IGN bought them. The whole "out of keys" situation is ridiculous because there should be no issue with generating enough keys for everyone aware of the giveaway to get one.