Because the ZMAX has a write protected system partition, Kingroot can only get you Temporary Root. Temporary Root is root that only lasts until you reboot the phone and is then lost. In order to get permanent root that isn't lost when you reboot or reset the phone, we need to install TWRP and use it to flash SuperSU.
[1] Download and install the newest version of Kingroot
from:
http://goo.gl/uaUIs2
[2] Download and install ZTE ZMAX TWRP Recovery 2.8.6.0
from:
http://goo.gl/0FsViN
[3] Download UPDATE-SuperSU-v2.46.zip
from:
http://goo.gl/vcjCwb
[4] Open and run Kingroot (might not work the first time)
If Kingroot succeeds then skip to step 6
[5] If Kingroot fails, go to app drawer, long press on Kingroot icon and drag it to the top of your screen where it says "app info." Then clear cache and data for Kingroot, turn the phone off, wait a few seconds, and turn it back on. Repeat steps 4 & 5 as many times as necessary.
[6] Open ZTE ZMAX TWRP Recovery 2.8.6.0 and click "Install Recovery" and grant root access. You should then see a popup that says "success." Once you have TWRP installed you never will need Kingroot again.
[7] Go back to app drawer and uninstall Kingroot and Purify.
[8] To reboot into TWRP, power off the phone, then press and hold the power and volume up buttons until you feel the phone vibrate, then let go of the power button while continuing to hold the volume up button for approximately ten more seconds.
[9] Once you are in TWRP recovery, tap the "Backup" button and select System, Data, and Boot (select SD card as backup location if you have one) and swipe to make the backup.
[10] Go back to the main screen in TWRP, press the "Install" button, navigate to the Download folder on your internal storage, tap on "UPDATE-SuperSU-v2.46.zip", and then swipe to install.
[11] Reboot System and enjoy.