09:55 질문입니다!

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.ktx.auth
import com.google.firebase.ktx.Firebase

class MainActivity : AppCompatActivity() {

    private lateinit var auth: FirebaseAuth

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        auth = Firebase.auth

        val joinBtn = findViewById<Button>(R.id.joinBtn)
        joinBtn.setOnClickListener {

            val email = findViewById<EditText>(R.id.emailArea)
            val password = findViewById<EditText>(R.id.passwordArea)

            Log.d("MAIN", email.text.toString())
            Log.d("MAIN", password.text.toString())


            auth.createUserWithEmailAndPassword(email.text.toString(), password.text.toString())
                .addOnCompleteListener(this) { task ->
                    if (task.isSuccessful) {
                        // Sign in success, update UI with the signed-in user's information
                        Toast.makeText(this, "성공", Toast.LENGTH_LONG).show()
                    } else {
                        // If sign in fails, display a message to the user.
                        Toast.makeText(this, "실패", Toast.LENGTH_LONG).show()

                    }
            }

                }
        }
    }

Log.d(TAG, "createUserWithEmail:failure", task.exception)

auth.createUserWithEmailAndPassword(email, password)
        .addOnCompleteListener(this) { task ->
            if (task.isSuccessful) {
                // Sign in success, update UI with the signed-in user's information
                Log.d(TAG, "createUserWithEmail:success")
                val user = auth.currentUser
                updateUI(user)
            } else {
                // If sign in fails, display a message to the user.
                Log.w(TAG, "createUserWithEmail:failure", task.exception)
                Toast.makeText(baseContext, "Authentication failed.",
                        Toast.LENGTH_SHORT).show()
                updateUI(null)
            }
        }