Complex sentence: When he is offered the position of assistant manager, he quits in order to focus on managing a chain of restaurants, and, later, his own new concept for an extravagant hotel, the Hotel Dressler.
Split into simpler sentences: When he is offered the position of assistant manager, he quits to focus instead on managing a chain of restaurants. Later, he builds his own new concept for an extravagant hotel, the Hotel Dressler.