On the next screen, choose which formats to install:
You'll also be asked whether to install for all users of this Mac (/Library/Audio/Plug-Ins, /Applications - requires an administrator password) or just for you (~/Library/Audio/Plug-Ins, ~/Applications - no password needed). Both are locations every AU/VST3 host scans. The AAX plugin is the exception: Pro Tools only looks in /Library/Application Support/Avid/Audio/Plug-Ins, so it always installs there and needs an administrator password.
By default, this plugin sends an anonymous ping when it opens and when you load a factory preset (plugin name, version, OS - never audio, project data, or anything personally identifying). On the next screen, check "Opt out of anonymous usage analytics" to disable this.
Restart your DAW (or run AU validation) after installing so it picks up the plugin.