Yes, you could take the free shuttle bus even if you don't check in the hotel. Well, here are my suggestions, when you arrive at Macau Ferry, please take the free shuttle bus to the Grand Lisboa, then you could walk to the Senado Square. After lunch here, you could take a cab to the Macau Tower which is only 2km away. Then, you could take the bus 21 from here to Ama Temple. If time still left, you could take the bus 21 to Venetian, and finally take its free shuttle bus back to the ferry terminal.