I have it set up at our school the following way;
My personal ipad has a the paid Klikaklu app on it (I also use it at home with my daughters). I have created a load of courses around the school and printed off the posters for students to scan the QR codes. The courses are all set up with staggered starts.
The student ipads have the free version of the app on them. They can play hunts,but not create (though I think the first few days of downloading it you can).
Students get a copy of the school map, with grid lines on them. The clues are all grid references, and off they go.
The courses are all saved and can be used at anytime - just need to check the photo locations are still the same - ie objects have not been removed.
Hope this helps