edit: nvm, missed a line in your first post.
Tried to update your game? (is it updated? small chance but still.)
both folder and exe file is located in the base folder of shogun 2 right? Many people puts it in the data folder which is wrong :p (i know you said you did, just hammering it home.)
mmmmmmmm here's what:
Redownload the mod, unzip it on desktop. mark the exe file and the folder, copy. go to shogun 2 base folder and paste the 2 items here. Try to see if it works now.
If not, delete shogun 2 game, redownload it and try again ^^
Oh oh question: Play on windows or mac?