Set CustomEnchantsWorld to empty array [], which means that the plugin enables all its effects on all world registered in the server. This should fix the "This enchant doesn't allow you to use in this world" issue. If you wish to only let the plugin take effect on a specific world, then follow the steps below:

1. Turn off server
2. Locate the config.yml in plugins/CustomEnchantments3
3. Enter your world in CustomEnchantsWorld section
Example:
- CustomEnchantsWorld: [ "private_world", "arena_world" ]
4. Save the config file
5. Start the server