Try https://mv3d.cutievirus.com/documentation and https://mv3d.cutievirus.com/external_tutorials perhaps? Poking around the demo answered a lot of my questions too. This requires a LOT of setup, but you can copy-paste a lot of it over from the demo to get you started.
Viewing post in MV3D - 3D Rendering Plugin for RPG Maker MV comments
No problem. I admit that I, too, tried to apply this plugin to an existing project first only for nothing to work. That deleted post up above is mine. It was only after doing some reading that I realized that you need to build the entire game around this plugin, not just attach it to something else and expect magic to happen. A bit disappointing, but the results are worth it.