There are several variants of this device. They do in fact all run android, Some are based on 8.1 and others run 10.
It's sold as the ZTE Cymbal 2 (Z2335CA) , ZTE Cymbal U / Consumer Cellular Link II (Z2335CC) and the Telstra Flip 3.
I have both a Z2335CA and the Consumer Cellular Z2335CC. The Z2335CA cant install apps but you can access ADB to disable the built in ones.
Tap on the build number a few times in the settings to enable developer options and turn on USB debugging. Then try the steps posted above.