I've also email support at itch.io.
Sorry there's no sound, it's noisy where I live. It seems like the Steam Key process has changed significantly. Now you click a link and are re-routed to Steam's web page. It doesn't matter if I'm on my desktop, laptop, phone, or tablet, the result is always the same. It says it fails to connect to Steam. I've also tried being signed into or NOT being signed into Steam when I start (the difference being, if I'm not signed in, it asks me to, then everything is the same). I've also tried having the Steam client open on my computer, it still opens Steam's web page, and everything else is the same. I've also checked my Steam account to make sure Lizard wasn't added, it wasn't.
If it was just a matter of copy/pasting a key, I would have been done in a couple of seconds. I mean, I've got hundreds of titles on Steam, and am a pro of GoG and HumbleBundle... Key pasting isn't exactly a barrier for me these days. Anyway, here's the video that shows the current (completely broken) process for getting the included Steam key:
-LeRoy3rd