First, lets start with what they symbolize.
Air. Air symbolizes freedom, knowledge. Those of air will be drawn to knowledge, and will challenge bindings.
Earth. Earth symbolizes durability, and defense. Those of earth, are sturdy and are drawn to protect others.
Water. Water symbolizes passiveness, and conformity. Those of water are often flexible, and good adapters.
Fire. Fire symbolizes power, and rebirth. Those of fire are strong, and passionate
Balance. Balance symbolizes tranquility, and harmony. Those of balance are often calm, and considerably level-headed.
Now, we take that, and put it in the astral realm. Each element would have their own style of creation, within the astral, their own strengths and weaknesses. Water would have more...smooth thought, they would have an easier time shaping the thoughts they have into creation. Earth, is more solid. They would have a simpler time with structures. Fire would have a more creative sprout, they would do a fine job with more artistic creations, like artwork. Air, has a more...knowledge-based approach, they would do better with simple things like scrolls, and other things that may include natural creations from woods. Balance, would have, very simply, an easy time with most things. But are sometimes prone to mental blocks.
Well, I hoped this helped to explain how our elements may tie into the astral realm.