I do not believe you can run Little Big Adventure on a MAC.
However, try downloading DOS BOX, a free DOS emulator, for MAC
here.
Run it, and see what settings it sets your sound to. Remember these for installation, or else you won't have any sound.
Then type help, and I believe it will teach you how to use it. Install Little Big Adventure 1 + 2, and try to play them using DOS Box.
Let me know if you have any issues or questions with installing it via DOS Box.