Does the adults need a membership to let the kids go in the pool and not swim???

Not sure not sure

If it is too good.

When they turn 14 they can go alone

Adult needs to be in the pool to supervise their children especially if they don't know how to swim. Adult needs to join as well. You can join for 1/2 year to try out to see if they like it. Of course children under 18 are free. If you have the NYC ID you can get a discount.