Why would a developer ask the your apple ID, seems odd -- maybe it's so fast easy that way..... (or at least offer this idea.. make me an admin user)
There used to be a way to share your screen via the Apple ID and FaceTime, but I thought it had been deprecated. But the developer may know a way I am unaware of. It is one thing to give someone your Apple ID but giving someone you Apple ID and Password is something entirely different and far more dangerous.