good luck man, personally im sure they do have a age requirement of 21 even though they say they dont.. but if you dont try you will never know, just be yourself, they exactly what they are looking for and will see through people who are trying to be something their not.
For you my friend, I think you need to prove you have a extreme amount of maturity due you being a bit younger, if you get to final interview and your application is sent to dubai, remember it has to be signed off by management and they have to see you are mature enough to move to another country..etc etc.. Good luck buddy and just be yourself.