I believe it should twist and pull up. If it hasn't been used, you might want to spray some liquid wrench towards the base (or an equivalent in the Netherlands). Welcome aboard.
The ski pylon should be able to be pulled straight up without much difficulty, once up it needs a 1/4 turn to lock it into position. If you are having difficulty I would suggest lifting the sun deck, getting a better grip on it and try lifting it again. If that doesn't work, let a spray of penetrating oil soak in for awhile then try lifting the ski pylon.