Activate USB debugging

Settings > About Phone > Tap MIUI Version several times to enable Developer Options.
Go Back and browse to Additional Settings > Developer Options and Enable

• USB Debugging
  (- Install via USB) Optionnal
• USB Debugging (Security settings)
• Enable view attribute inspection.

Now open command prompt. Type the following codes:

adb devices
adb shell
settings put global tether_dun_required 0
reboot

I’ve bought Xiaomi kenzo (Redmi Note 3) nextday after I’ve found XDA theme about the port and donated to Akhil (porter) to support him.