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.
Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.