Deluxe Hub Plugin

I have installed the deluxehub plugin on my server because I need a good hub plugin. I installed it on the server and it also works but if someone comes into the server he is either the skin type "Alex" or "Steve" are both standard skins from Minecraft. So if someone is on the server so everyone on the server is either alex or Steve you can change that not everyone with standard skin is there something or what can I do that everyone in the server has his own skin

The skins come from Mojang servers, if they don't deliver, nobody has their skin. You can't change that.

But why doesn't that work, why don't they deliver?