Reach is important
I don't know about wing chun, but in boxing, arm length (reach) is considered a significant advantage independent of other factors. It's important enough to report the "wingspan" of each fighter before a fight, as part of comparing other physical attributes like height and weight.
Generally speaking, many physical attributes are advantages, but significant skill can overcome these disadvantages. However, with equal skill, the fight will often be determined by those physical attributes. One should endeavor to improve those physical attributes that can be improved (e.g., strength, explosivity, speed) and to develop skills which overcome those physical attributes that cannot be changed (e.g., height, reach).
Having long arms, ceteris paribus, means there is a zone where I can hit you but you can't hit me. That means that you could be standing in my "pocket" getting hit while you are unable to return fire meaningfully. (If the fight or match involves kicks then that is a mitigating factor, but that simply means the reach of your legs is something to consider too.) That's an enormous advantage. You should work on developing techniques to overcome it.
Overcoming an opponents' longer reach
The solution is to avoid standing within the opponent's range, except when you commit to closing the distance such that you can hit them. Therefore extreme long range and extreme short range become your friend, and the middle distance your enemy. Refuse to accept standing where the opponent can hit you but you cannot hit them; either move back or move forward. Use proper footwork, angles, and evasive tactics as you do so, but do not stay there.
I don't know how much of a subject this is in wing chun, or if you'll get a chance to practice it in sparring by starting not touching, but it's an important skill for fighting. If most people have longer reach than you, then you'll want to get very good at explosively closing the distance and either A) landing your hits at close range quickly before explosively stepping off on an angle or B) winning at close range, perhaps with dirty boxing, throwing the opponent down, or taking the fight to the ground.