Extra info to whoever handles this, to shortcut some questions... Discussed here initially: https://forums.dovetailgames.com/threads/ts-rewards-flatcar.77182/ OP owns (claims to) both Sherman Hill and Köln-Koblenz, but probably a different package (or Steam would automatically add the apps, I received several things that way over the years).
And as I mentioned in the other thread you have to raise a ticket with DTG. because they need further details. How do you expect them to arrange for this to be added to your Steam account if they don't know what it is?
You have now been told in two different thread by multiple people what you have to do but you choose to ignore us. Why do we bother?