The OMChorma and OM2Csound libraries must be unpacked and installed in one of the specified external folders.
Set the library folder in teh OM / Libraries tab folder if necessary, push “Apply” to record the change.
Note: At this point your library is registered in the OM libraries, not yet loaded.
Open the Library Window in OM (shift + cmd + P), open the library folder and load the OMChroma library.
If you did not load the OMChroma library and open a patch requiring it, a window will appear proposing you to load the library (if available). Answer yes to this window.