Make sure you have Train Simulator 20xx installed. If that gives you no dice with the installer try seeing if you can manually point it to where the TS Directory is.
Its commonly this path, C:\Program Files (x86)\Steam\steamapps\common\RailWorks but if you have multiple drives in your computer like me, it could appear as something like F:\Steam\steamapps\common\RailWorks
Hope this helps
