AAX
Pro Tools only loads AAX plugins, so a VST3 download won't help you there. Every plugin here ships as a native AAX build for Pro Tools on macOS and Windows, and you don't need an iLok to run it.
The real plugin engine, running in your browser: same DSP code and presets as the VST3/AU/AAX.
/Library/Application Support/Avid/Audio/Plug-InsC:\Program Files\Common Files\Avid\Audio\Plug-InsInstalling and using plugins in Pro Tools.
AAX (Avid Audio eXtension) is the plugin format Avid made for Pro Tools. Pro Tools does not load VST or AU, so a plugin needs an AAX build to work there.
No. You activate with a license key from your receipt email. The AAX builds are signed for Pro Tools, but you don't need an iLok account or dongle.
Yes. Pump, Spread and the Keys electric piano are free and ship as AAX, so they load in Pro Tools on Mac and Windows. Pro Tools also includes stock plugins such as EQ3 7-Band, Dyn3 Compressor/Limiter and D-Verb. Any free plugin you add from another developer must have an AAX version.
Any pitch correction plugin with an AAX version. Tune ships as AAX for Pro Tools on Mac and Windows and runs in real time, so you can track through it. Antares Auto-Tune and Melodyne also have AAX versions. Insert the tuner in the first slot on the vocal track, before EQ and compression.