What exactly are you trying to do? My guess is throttle a hydraulic FCV (Flow Control Valve). OK, the valve is a proportional valve and you have the driver for the valve. I assume you have the 24 volt valve since I see plenty of 24 volts in your images.
So you have the valve body and you have a controller designed to work with your valve. The controller sends a signal to the valve sending the valve a command for a position. Reading the data sheet, the controller data sheet, and looking at the partial data sheet you posted they show a pot used for position control of the valve. One end of the pot is tied to Gnd and the other end to 4.5 volts out of the controller. So the voltage on the pot's wiper can never be less than zero and never greater than 4.5 volts. Don't want that? You had a digital pot in the mix for awhile?
So you can use an external pot to control the valve body or just simply set a voltage between 0 and 4.5 volts between Gnd (Brown) and Green, The image also points out Imax and Imin which you adjust on pots inside the amplifier driver.
Again, what exactly in detail is your objective?
Understand also the Dither is applied by the valve body driver amp.
Ron