lunatik.13

Hello guys. i have problem like this. when i want to install any save game or any other IPA/FILE thich needs IFUNBOX or any other managers, i download ifunbox and when i install it says something like this "Your device is not jailbroken or it is over ios 8.3+", i mean that i have NON-JAILBROKEN iphone 6S and does it mean that i cant use it? i currently have IOS 11.1.2 , please explain me anything if you can/know. THANKS.