Yes lime trees do need to be pollinated and that can be done either manually by hand and a brush or through use of bees that naturally pollinate the lime trees.
You can take a brush such as a pain brush and then touch each flower with the tip of the paint brush or feather to gather the pollen, then brush each stigmas with it in turn.
That will then pollinate the lime trees and then within a few years to 5 years the lime tree should begin producing fruit.
Lime trees can take awhile to produce fruit so you need to have patience when growing lime trees or other fruit trees so that they produce fruit.
But overtime they will eventually produce fruit.