It still doesn't work, but I was able to load StudioManager by doing the following :
I copied the missing files (as reported by the crash reporter) and renamed them so that they match. I took them from the lib folder that is created in /Applications/Yahama/StudioManager/lib and I pasted them in /usr/lib/.
For example, I copied libsmh-qtoptserver.1.0.0.dylib into /usr/lib and I renamed it libsmh-qtoptserver.1.dylib. Same with libsmh-qt-mt.3.dylib.
I also had to rename the LS9 library to libls9-qt-mt.3.dylib for it to load.
Now, StudioManager loads, but the Re-Synchronize button is always greyed out in the editor.
Before doing that, I disabled system integrity protection by doing "csrutil disable" in single user mode (reboot holding command-R). Not sure if it is necessary.