I came across the kua number concept many years ago. From my limited understanding, depending on the lunar year that you are born in and your gender, you are assigned a number based on calculations. For each number, there are a set of directions which are supposedly lucky and unlucky for you. You are encouraged to face these directions as much as possible. There’s a direction for love, one for health, one for success and wealth and one for growth.
I don’t know the interaction between flying star feng shui and the kua number. And this could be an important qualifier of the use of the kua number.
There are online calculators of your personal kua number, along with the lucky directions. I suppose there’s really no harm in trying out these directions if you don’t let this concept take over your life.