The mod for version 1.16.5 is built for the Forge mod loader and is not natively compatible with Paper . Paper is a server software designed for plugins (Bukkit/Spigot), whereas Mystical Agriculture is a content-heavy mod that requires a modded loader to handle new items, blocks, and mechanics.
If you must use Paper plugins alongside Forge mods, you can use a "hybrid" server software designed for 1.16.5. Mystical-Agriculture-Mod-1.16.5.jar
: Download the 1.16.5 version of Forge and its necessary dependency, Cucumber Library . The mod for version 1
This is the standard way to run Mystical Agriculture. Both the server and all connecting players must have Forge and the mod installed. Mystical-Agriculture-Mod-1.16.5.jar