In order to use the Garritan Libraries in Ableton Live, verify that the proper ARIA Player Components are installed in the Audio Units or VST Plug-In folder that Abelton uses and that the Garritan ARIA Player is showing in your Plug-In Device Browser.
To verify the pathway, open a Live Project and open the program's preferences:
Macintosh: Live Menu > Preferences
Windows: Options Menu > Preferences
In the Preferences Window, click the File Folder category on the left. Verify that "Use Audio Units" and/or "Use VST Plug-In" (either System or Custom Folder*) are turned On.
*If you are using a Custom VST Folder, verify that the ARIA Player VST DLL file (either 64-bit [x64] or 32-bit [x32] depending on your version of the application) has been copied to this folder. If it is not present here, you can copy it from the following locations:
Macintosh: Macintosh HD > Library > Audio > Plug-Ins > VST
Windows: C:\Program Files\Garritan\ARIA Player\VST
Be sure to click "Rescan" under Plug-In Sources in Live's File Folder Preferences to refresh the Plug-In list.
Once these files are in place, the ARIA Player will be available for use as a Plug-In within Live.