This is a Steam key. you must have a Steam account to redeem it.
Even if you are already subscribed, you can still get it free.
https://www.humblebundle.com/store/dirt-rally?hmb_campaign=freegame_2019_homepage_dirtrally&hmb_medium=banner
The free download is not a Steam key.
Even if you're already subscribed you can still get it free.
https://www.humblebundle.com/store/jalopy-free?hmb_campaign=freegame_2019_homepage_jalopy&hmb_medium=banner
The deal ends May 11, at 10 AM PT / 1 PM ET or while supplies last
The free download is a Steam key, you must have a Steam account to redeem.
Even if you're already subscribed you can still get it free.
https://www.humblebundle.com/store/age-of-wonders-iii
For a limited time, get a free copy of LEGO The Hobbit when you subscribe to the Humble Bundle newsletter.
Limited Time Offer Ends December 15 at 10 a.m. Pacific time
Edit: It looks like they've run out of free keys...