Ninjadoodle yes, no server required. This is all running off our own cloud.
Today or early next week I'm releasing a big update that will break implementation of your own leader board (sorry for this, but it's not yet all released officially yet).
These changes are required because we're introducing an authorisation service which allows players to sign into your game (EG with Apple, Google, Facebook, Discord etc). From this you are given a session key which you will need to post with leader board requests instead of just a player name.
This allows us to easily add other services going forward such as cloud save. Bear with me - I'm nearly done with this and then I will update all docs and hopefully Ash will be able to get the updated plugin in the next beta.
I'll try to remember to update this post.