What does a private server require?

Hey everyone. What does a private actually require other than the game files?
I'm quite new to the private server part so please don't bully me. :P

I'm asking because I'm currently trying to figure out how Aura Kingdom accesses Aeria games server but unfortunately, I don't know where to start. I've so far extracted the game files and the game db but the rest is pretty blurred out for me.

Thanks for reading. ^^

the server files

First of all it requires knowledge. Without it you won't get anything done.