We have a public fork of JUCE that among several other modifications also contain the tweaks to the AAX plug-in client (modules/juce_audio_plugin_client/juce_audio_plugin_client_AAX.cpp) for ARA support: GitHub - acondigital/JUCE: JUCE fork with some customizations for internal use at Acon Digital
You’ll need to add the header files for the AAX ARA bindings that you obtained from AVID if they accepted your project.
Best,
Stian