You're in the right place, but i don't think Lord Ketlaar is the one you need. The person you need is near the exit in the south-western part of the building, and looks like a wizard. (i forgot his name ) He standing rather close to Tolgerias (who will be smack in the middle of the hall when you enter the building).

The convo will not immediately lead to an option of buying a magic permit, you'll have to go through a few lines of convo first.

I'm pretty sure his name is Corneil or something similar

Suga's right, Corneil or something similar is the guy you need. It's quite expensive though, in the beginning of the game.