You need to divide that number with 4. So he won't get anything from singles but will get 30 points from doubles (120:4) and that will get him till, like you said, 51st position.
My point was that if Veger had won the final
he would have become the top-ranked Croat. He would have picked up 90 points [(180 regular points + 180 bonus points = 360 points / 4 = 90].