how much is total roundtrip fare hk-macau ferry on a apr 14

As far as I know, there is no round trip ticket for the ferry.
The single ferry from HK Island costs 159HK$ per person on weekdays, 172HK$ for weekends and holiday during day time and 195HK$ at night.
For more detail information, you can look on the official website of Turbojet.

For getting the ticket, I suggest you consult the exact location from your hotel. I find at the official website of Turbojet, which shows that the booked tickets can be gotten at 3/F Shun Tak Centre, 200 Connaught Road Central, All China Travel Service branches, Shun Tak Travel, Shop No. B12, Basement Floor, Shun Tak Centre and other Self-Service Ticketing Kiosks.