I will be staying in Sintra Macau, how do I go to the ferry terminal to go to hk?

The ferry tickets can be both bought online and on the spot. In my opinion, you can book in advance, so that your trip will not be disturbed.

From your hotel, you can easily walk to the Grand Lisbo where you can find the free shuttle buses for the Maritime Ferry Terminal.

Stayed in Sintra during November 2013 and I took the free shuttle bus provided by the hotel to the ferry terminal & transit to HK.
Just ask the hotel the shuttle bus schedule and the ferry schedule. Then you will be able to adjust your time. The hotel will have a list of the ferry schedule.

I bought my ferry ticket at the ferry terminal on the spot.

Hope this help.