Is the architecture the same? (32-bit and 64-bit) Did you only make VSTs or also AU plugins? I have only tried exporting to VST as I have no Mac.
With VST, you need to provide both the VST and the .csd file in the same folder. You can read more about distributing here: http://cabbageaudio.com/docs/distributing/
Did you provide your users with an installation of Csound? It does need it in order to function. You could make an installer that installs all in one.