Try that link. That should be supersu 1.8. I just flash it through TWRP. I always withe cache and davlik before and after I flash as well. But that should fix you
Dude slim ROMs are bad a**! It comes with its own slim chat. After talking to those guys Idk if its a 4.4 thing or a slim rom thing but there's an option in dev settings to enable root.