To install Apple MIDI Manager you simple drag the file "MIDI Manager" into your Extensions folder and restart your computer. This file is in "Midi Manager Folder" inside Ballade folder.

Additionally you can drag the file "Apple MIDI Driver" to your System folder if you plan to use an external MIDI device, AND/OR you can drag the file "OMS MIDI Manager Driver" file to your System folder if you plan to use OMS in paralell with Aple MIDI Manager and also let OMS to manage external MIDI devices.
"OMS MIDI Manager Driver" is on MacTron Xtras folder inside Ballade folder.