Oh, that sucks mate :/
im on Lollipop 5.1.1 and it works for me.
i think youll need a ROM with i think its called De-odex.
I wouldnt be flashing stuff too much though, bricked my old s3 a while back because i tried like 10 ROMs within a week.
Yh so just try do a little research on a ROM that actually supports Xposed, it is a bit of a piss take tbf, personally i did it for the pokemon go control mods