I got a text file called steamkey and when I opened it, it contained this:

Thank you for your purchase!
Let's activate the key on Steam. It will be easyer to manage update for the PvP

That's it.  Where's the actual key???

Humm it looks to be a bug with itch, the key should be inside

Can you try do download again. I change a configuration

Now the download button for the steamkey says "Preorder" and is grayed out, cannot click it.