Our automatic installer comes with Minecraft/Bukkit/Spigot/Paper already included, so you can install them with just a few clicks. However, if you are looking to install a custom version, that's still an easy task:
- Download the JAR file you wish to run on your server
- Rename it to custom8.jar if you want to use Java 8, or custom16.jar for Java 16
- Log into Multicraft
- Navigate to the file manager (Files → File Manager)
- Upload your JAR file into the jar directory
- Select one of the custom options from the Multicraft's JAR Menu (according to the Java version you'd like to use)
- Restart your server
Note: if you are downgrading to an older version, you might want to remove the existing world, as it probably won't be compatible with an older game version, thus crashing the server.
