2. Configure your server and run it once with Spigot/PaperMC to generate a plugins folder. You can also make the plugins directory manually. Close the server after it has created the plugins directory.
3. Download the latest public release of mcMMO from the Spigot page.
4. Drag and drop mcMMO.jar into the plugins directory.
The next time you run your Spigot/PaperMC server, mcMMO will enable itself and generate many configuration files for you to modify in server_directory_here\plugins\mcMMO.
Choosing the appropriate mcMMO version
There are many versions of Minecraft, Spigot, Paper and mcMMO. To choose the best version, refer to Version Compatibility.