To me Atlantis feels like an advanced version of Cartagena and because my game closet is overflowing I traded Cartagena and now just use Atlantis components to play it when I want the lighter, shorter game.
All you need to do is add enough 3 meeples for each player and 6 for a fifth player. (I just use my walk the plank meeples)
To play just lay the tiles out randomly to form the path. You can use both sets for a longer game but we just use the A tiles because we play this as a filler.