Re: Mod will not start.
Didn't know it was a pre-kingdoms mod with the medieval2 executable in the BAT file instead of kingdoms.exe
My guide basically tells you to copy medieval2 (steam only has that one) and then rename the copy to kingdoms (the disk has this one, too) - that is for all the kingdoms mods out there. You should still arrange that you have both file names present in the main directory in case you decide to play a kingdoms mod later.
NEVER edit Steam's launch option in the library (right click game on there, choose properties to access it), it should be empty, creates all sort of mess otherwise.