GND is not the chassis.
They should have call it -160v.!! (to chassis)
Study the big circuit and you see the negative of rectifier is marked GND.
There is +160 and -160 on the capacitor(s).
This circuit will only work with a BLDC motor.
If operation is erratic then there are whiskers on the magnet in the end of the motor.
You can remove whiskers with adhesive tape. It a common problem with BLDC motors that have hall sensors.
To test the controller, in a safe manner I have run the HV part on only 40v and the motor will run albeit slowly.
You still need to satisfy all the other 4 supplies.
Running the whole thing on a 1:1 isolation transformer (200W is OK) at light loads is a safer way to do testing.
Running the motor out of the box, make sure you clamp it down and earth the case or wear insulated gloves.