Copy SuperSU.zip to both the phone’s internal storage
Connect the phone to the PC via USB cord while switched On and boot it into Fastboot (as instructed in the Bootloader unlock guide; don't forget to re-enable OEM unlocking and USB Debugging)
When the phone enters Fastboot, load the Philz recovery to the phone by typing the command below then pressing Enter
Code:
fastboot boot recovery.img
The phone should automatically boot into Philz recovery mode (depending on which you flashed)
Do a full backup by tapping Backup (Recommended) then proceed with the guide once done
If Philz offers to root the phone, select NO
In Philz recovery, tap Install
Navigate to the location of the SuperSU.zip on External SD card and select it
Reboot the phone normally
Confirm Root by installing and running Root Checker