I recogmend using Multiverse to create a new world because the plugin uses worldborders to set the map size.
The permission is : risinglava.games.risinglava
How to customise: You can customise the items in the GUI by:
Finding your servers plugin folder
Finding the folder RisingLava within your plugin folder
Open the config.yml and change the name and item properties within the slot fields (please note I do not recogmend moving the items slot because this could cause issues)
Thanks for trying my plugin! Please leave a review!