Soft-Start on chinese 400W spindle

Hey there,

My MPCNC is currently running with a 500W chinese Spindle (like this one 400W-Spindle-Motor)

This spindle got an external controller for speed and stuff.

Seller claims it has got: “4. soft-start function. Prevent excessive current caused by the motor and power damage (default 0 seconds soft start), 0-5 seconds adjustable.”

Any idea how to adjust/enable this?