Oh, my bad, my mistake. I forgot the most common problem in these cases. As you can see in the wiring diagram, the servomotor signal pin has to be connected to pin 7 of the Arduino (it is marked in another color).
When I designed the board, I made the mistake of thinking that pin 41 of the Arduino Mega could be used as PWM and it is not, so the solution is to unsolder from the Control PCB the pin that would be connected to pin 41 of the Arduino and instead solder a jumper wire to connect it to pin 7 of the Arduino.
I hope this solves the problem!