if you bought GridRoad, it'll be in the same place you download the game from on itch.io
If you got it for free you unfortunately don't get the Steam key.
Oh ok, I see. Thanks for mentioning it! You should probably pin your reply or put this as a note in the downloads page of the game in itch.io/in this product page at the top, because I am sure a lot got it for free XD
