Welcome to the MMOItems Wiki!
Get MMOItems Premium over SpigotMC. If you'd like to try out the plugin first before buying it, you may get MMOItems Legacy. It is an older version of MMOItems which does not offer any many features as the premium version. It only supports Legacy (1.8-1.12.2) server builds.
An installation guide is available here! Many issues are related to plugin builds not being installed the right way, since the installation process highly depends on your server version and plugins.