The motor hat is only to control the stepper motor that will be used for the focuser. It is not intended to be used to control the mount.
I know the "mount" contains the the RA/DA motors. And the hand controller controls those motors. The expectation is for Astroberry (via Kstars/Ekos?) to control the mount. The description for Astroberry includes it's ability to do this.
I am using a USB cable to connect the Astroberry/Raspberry Pi to the USB port on the bottom of the hand controller.
I do not understand what the ST4 port is.

Please understand that I am only asking for the Astroberry/Pi to control the mount.