This happened to me when I was trying to run the game with DAGGER.EXE, I kept getting the error even if the paths in the z.cfg file were the correct ones.
Try to run Daggerfall with the FALL.EXE Z.CFG command instead (just make a dagger.bat file with the text "fall.exe z.cfg" and run it in dosbox). It should work fine.
EDIT: I see you got it work. Run the setup.exe to configure the soundcard and get the sound working.