The problem (well, one of the problems) with trying to implement battle systems in your game is the sheer size of them, and how much tweaking it takes to get it all working.
If you've read the tutorial then you probably have a good enough understanding to implement most scripts (for example the one made here
is just plug-and-play, you paste the code in the script editor and it will work).
But with battle systems I've seen it where you need to copy the skills, items, weapons, armours, elements, states, and the first dozen variables/switches from the demo before it works.
If the battle system is the biggest script in your game I would recommend using that demo as the starting point for your project, import your resources in to that demo, and work around it, it's usually a lot easier.
You can open the game's folder (Game >> Open Game Folder) and change the Title= setting in Game.ini to suit your actual game's name, and I believe you can copy entire maps over so it isn't too difficult.