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:
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 is being worked on. Look at the Sitemap for the individual pages for now.
However, it is heavily advised to download, check and experiment with the demo project. There is no better way to understand how the plugin works than to see for yourselves and play with it a bit, after all.
Adding to that, if you are using MZ3D, it is still advised to download the MV3D demo project, as it has some example maps the MZ3D one does not. To open an MV project in MZ, copy a “game.rmmzproject” file of an MZ project to the MV one's.
And beyond that, there are always tutorials.