Garritan libraries will install the necessary components to your Mac's Plug-In Component folder. Then you need to load the ARIA Player in a GarageBand instrument track.

To load an Audio Units plug-in in a track:

  1. Double-click the track’s header to open the Track Info pane if it is not already open.
  2. Click Edit to view the track’s effects in the Edit tab.
  3. To add an Audio Units effect plug-in, click one of the empty effect slots, then choose a plug-in from the Audio Unit Effects section of the pop-up menu. Audio Units plug-ins appear below the built-in GarageBand plug-ins.
  4. To add an Audio Units instrument plug-in to a Software Instrument track, choose the plug-in from the Sound Generator pop-up menu. Audio Units instruments appear below the built-in GarageBand instruments in the pop-up menu.
  5. If a plug-in has presets available, choose a preset from the pop-up menu directly below the effect name.
  6. To adjust a plug-in’s settings, click the large rectangular button next to the effect name, then change the settings in the Edit window that appears.