I added c-rpg launcher as a non-steam game and did the same to my warband.exe
Still when I launch the game throught c-rpg launcher I can't use overlay ingame.
P.S. Don't post obvious things like "turn on the overlay". I did.
You have it on steam, and therefore due to the fact its not a steam version you can play it wihout using steam, therefore when you run the game through the c-rpg launcher it will automatically detect the original install (which is your version that is not linked to steam) i used to have the same, until i installed it just through steam.
Uninstall the game, use the CD-key through steam and download it then just put cRPG back on.