You can only do what you ask if you INSTALL the program onto your external drive (if it allows yyou to.) - Just copying the mian program folder across will leave many bits inside windows folders on the C drive, which refer to/are used by the program - and they'll be in, or pointing to the wrong drive.
However - is it the program you want to move - or the music library - I suspect it may be the latter. If you look at the settings in Tools - Options - Location to save imported files - you can readily change this to a location on your other drive.
Then the sizeable stuff all goes onto your second drive - just the program remains on your C drive.
(My grandson has a Sony mp3 plyer - so I have the software on my system, as luck would have it!)