Can a hotel in Shangri-La Island, Maldives accommodate three people in one room?

Yes, you can. It depends on the room type.

How many rooms can accommodate four people (two couples)?

You said Ctrip, they are subcontracted. As long as they have a special island, time and room type, they are all subcontracted.

You can find another agent, and you can do as you ask, provided that you know the room type of each island first, then tell them what room type you want to book, and then they will ask Male to check the room type and time you want to book, and if so, you can book it.

There are many rooms on the island, but if they are big, they can actually accommodate several people ~ of course, the price is much more expensive than ordinary rooms.