I just downloaded and skim read the manual and agreed it is a bit contradictory. Also 90% of it is setting up the Ethernet !

I’m sure you need the analogue inputs port so I would power the board up with the 5V supply then check the voltage of the ports with “12V” coming out. If it really is 12V then I’m not sure what steps are required to get this to represent the full speed range as I’ve only ever gone direct to the inverter.

In any case one end of the pot would go to “12V” the other end to 0V and the centre terminal to one of the analogue inputs. All of these are on the analogue port.

Somewhere I guess you configure the centre terminal input pin to be the speed signal in software but have never used uc300eth so hopefully someone can help confirm.