I don't have a Arturia controller.
But keep in mind, that it's a controller and not a synth. A controller output midi notes.
Middle C is midi note 60. In Hertz middle C is 261.625565 hz in a A=440 hz tuning.
In different software middle C can be labeled C3-C5, depending on the software.
What you can do is to check on which note your controller send out midi note 60.
The software you use should then send out a 261.625565 hz C note, if the software is correctly tuned to midi note 60.
On my Novation 61 key controller midi note 60 is the C that start the third octave (the third C note) - so there is two octaves below and 3 octaves above this note. In your case it would be the nearest C left of the middle of the controller. If i understand you correct, then you perhaps think middle C is the one to the right of the middle of the controller.
On a standard real piano middle C also is left to the center.