The K-theoretic Gromov-Witten (KGW) invariants are deformation invariants of a complex variety defined by counting curves. In this talk, I discuss my work on the generating function of the genus-zero KGW invariants of type-A (partial) flag varieties, a computation motivated by the 3D mirror symmetry. The method is based on the idea of abelian/non-abelian correspondence. I also discuss further applications of this method in studying the KGW invariants of GIT quotients and their associated q-difference equations.