The issue appears to be El Capitan's new System Integrity Protection which prevents writes to /usr/lib (as well as other directories) unless the installer is signed by Apple. I was able to get Studio Manager and the M7 and LS9 editors to install and run by disabling SIP and reinstalling. I then ran Studio Manager, then reenabled SIP.
I did NOT need to copy library files or rename them (as suggested here:
Yamaha Studio Manager with El Captain | Apple Support Communities )
so it appears the Studio Manager does the necessary copies that are required (when SIP is disabled).
I no longer have an M7 or LS9 to see if it actually controls the console. Maybe someone else can test this.