MV3D is a 3D rendering plugin for RPG Maker MV.
It requires your MV to be version 1.6.1 or newer.
MZ3D is a version of MV3D adapted for the later RPG Maker, RPG Maker MZ.
In there you will have a demo version of the plugins, with some functions missing, and a demo project to see it at work.
Fot the full product, you can buy the plugin on the respective itch.io, or become a patron on Patreon.
To add the plugin to a new or existing project, download the proper plugin zip file, instead of the demo zip file, and extract the files right inside your project directory.
The folders are already set to put the needed files on the proper folder.
Then, load mv3d (mz3d in MZ) as a plugin on the Plugin Manager.
Now when you run your game, the map should be rendered in 3D.
There is, of course, a need for some customization. For instructions on those, please read the documentation.
A more detailed, wikia-like version being worked on.