Visa on arrival!

Hi, I am an Indian national whereas my parents are Nepali passport holders. We have booked a trip to Hongkong, Macau and Disneyland lasting 6 days. I know Indian passport holders can get a VOA in both Hongkong and Macau but I am confused about my parents. My tour operator said that they can also get VOA but all the sites that I've visited state that they have to apply before they reach Hongkong & Macau. My parents presently live in India and we will be flying from India as well.