I installed a few of the Nebula 4 libraries from the sister site and wanted to try them out. I've never used Nebula before. I opened Nebula and then opened something via the Nebula Finder. Some VSTs work and some don't. Some don't display a GUI and others can't be operated because the buttons keep jumping back. This plugin now says that I should open it as a plugin, but it doesn't appear in my Studio One VST list.

 

if the sliders are jumping back, it means the plugin did not have or find the related files for those parameters in the correct place, does not have access to them, or the DAW samplerate for the session you have opened does not have corresponding files for it.

If you just installed something and you do not get the plugin version showing up in your Acustica plugin menu, did you not reboot yet? It does that on Mac even. Sometimes.

You're pretty close to it working.

 

You need to create VST3/AU instruments using the setup files, that why it's showing up that msg