It was there for me, but to me the button looks like it'd be grayed out but it still gave me a steam key so it was just how it looked. It was near the bottom of the page underneath all the download buttons, just says claim key or claim steam key somethinglike that. I also did it from my phone, if that changes anything. Haven't tried on my pc so idk. Oh one last thought, if don't see a button but see the words click the words n see if that does anything. 🤷♂️