CubedCraft offers 3 different rank plugins you can use on your Player Server. These plugins are called LuckPerms, PermissionsEX and GroupManager.
LuckPerms is, in most people's opinion, the best option. It can seem slightly more complicated to use however, it has the most capabilities.
PermissionsEX is another option, similar to LuckPerms however not favoured as much by most users.
Finally, we have GroupManager. GroupManager is considered the worst for capabilities by most users however can seem the easiest to use.
You can install a rank plugin at https://playerservers.com/dashboard/plugins
once you have created a CubedCraft account with /register (tutorial on how to register: https://playerservers.com/knowledgebase/article/3-how-can-i-register-on-this-website
) or you can install them ingame using /control.
Tutorials for each plugin can be found below however, I reccomend you also do your own research:
I hope this helps!