I want to implement password authentication

I understand what 3 means, but I don't know exactly what to do

"Since you misunderstand the meaning, it may be ""I don't know what to do""

"The word ""form"" is used in many ways, but here it means ""input screen""."In other words, if you have a user registration screen in the app, and the user enters his or her email address or password and presses the "Register" button, he or she says (before going to 4) "Verify the new account required by the app."

As for 4, I can understand to a certain extent that it is closed, but I don't know where to put it in AppDelegate

For this reason, instead of "where in AppDelegate" it should be described as part of the "Register" button on the user registration screen.

You may actually want to see more specific information about what to do, but the details depend on the content of the system application you are planning to create, so look it up yourself as much as possible.

"If you understand that ""application registration form"" is a user registration screen that exists in the app, you will be able to find a sample application of Firebase with a user registration screen."

Still, there may be some things you don't understand, but if you ask a question that you don't understand after including the code that you've tried so far, some people will try to follow the code as much as possible.