Ableton Live (Mac) supports VST2 and AU.


32 Lives 1.0 supports Audio Unit (32bit) to Audio Unit (64bit) only.

32 Lives 2.0 supports Audio Unit & VST2.


For Audio Unit support, please make sure you've turned on  "Use Audio Units" under Ableton Live Preferences -> Library.

For VST2 support, please make sure you've turned on "Use VST Plug-In" (system and/or custom folder).