It’s Künstlerisches Betriebsbüro, and if THAT rolls off your tongue, your German is pretty darn good! It’s always called the KBB-kah-bay-bay (no dphthong, please) and you’ll probably have more contact with them than anyone else in the administration. Even at auditions, it’s the first place you’ll be directed to. They handle the daily rehearsals and activities of the theater including auditions, so with any luck at all you’ll get to know them well. And make sure you are polite and professional to these hard working people…