Treadmill Calibration on Forerunner 45

I need to calibrate my treadmill on my new Forerunner 45. According to the manual after at least 1.5 km press stop.

To calibrate the treadmill distance the first time, select Save.
The device prompts you to complete the treadmill calibration.

To manually calibrate the treadmill distance after the first-time calibration, select Calibrate & Save > Yes.

On my watch, I can only choose Resume, Safe, or Discard. There is nothing about calibration.

Can someone explain?