RLC.stl is the main body of the box. I print it as it is (top of the box up) with support inside the box, depending on the type of your machine you might want to remove the embossed letters on the top face and print face down, it will save you some plastic, no support mess to clean etc..
poklopac.stl is the bottom cover of the box. Print it on the side to have max strength of the hinge. print with 100% infill (or less if your machine is not calibrated properly)
jezik.stl is the lip, the leg that allows you to hold the case at some degree up, it latches to the hinge on the bottom cover, also print on the side for max strength, if you print flat it will break when you try to latch. print with 100% infill (or less if your machine is not calibrated properly)
Video showing lip function (note this is before the final print so here the bottom cover is manually cut to find the proper dimensions and the lip is 5mm shorter then in final version)