i have the same problem do you fix it? and how?I'm trying to root my m8 for the first time and am experiencing the exact same thing..... It says there is no SU Binary installed and Supersu cannot install it. Any ideas why?
The only thing that worked for me was running Sunshine to get S off. Then I ran Kingroot (you can google the app) to get temp root and installed SuperSU.
After that I removed Kingroot and with S off and SuperSU it works fine on 5.0.1.
pls share the link to Sunshine and kingroot. can't find dem on playstore