Im not sure if 그들 and 그녀들 is exclusively male and female groups respectively, or the latter is a mixture of both. Can someone help clarify this?
그녀 is technically she but nobody uses it here in korea. You would just say 그들 unless it's written then you can use 그녀들 without it being weird
그들이 엘리베이터를 만들어요.