Take the plugin. Or the app.

The installer puts the plugin in the right place for you — use it unless you have a reason not to. Quit your DAW first; neither OS can replace a plugin a running host has open. The zip is the raw bundle, for locked-down machines or if you'd rather place it yourself:

• Windows — C:\Program Files\Common Files\VST3\
• macOS — /Library/Audio/Plug-Ins/VST3/
• Linux — ~/.vst3/

Then rescan plugins in your DAW. macOS builds are universal (Apple Silicon + Intel).

And the other half

The plugin is where the session is. The app is where the camera is — it is how you photograph a headstock and file a guitar, and the plugin builds around whatever you filed. Same account, same library, no second purchase. Both apps are out now, and free to download like everything else here.