Error connecting Firebase to Android app

I'm trying to implement Firebase in my Android app but I can not get it to work. I tell you the steps that I have followed

  

build.grade

 classpath 'com.google.gms:google-services:4.1.0' // google-services plugin

  

app / build.grade

implementation 'com.google.firebase:firebase-core:16.0.4'
implementation 'com.google.firebase:firebase-auth:16.0.4'
}
//Esta linea esta fuera de las dependencies
apply plugin: 'com.google.gms.google-services'

Once this is done I have made a sync now and it has not given me any problem. But at the time of making a record I get an error and it tells me that the user could not be registered and I do not know how to do it because I have already tried doing so and following the steps of the firebase from the android studio itself but the lines that I added the assistant that to the gradle does not compile. I leave here the class code .java

public class MainActivity extends AppCompatActivity implements 
View.OnClickListener {

//defining view objects
private EditText TextEmail;
private EditText TextPassword;
private Button btnRegistrar;
private ProgressDialog progressDialog;


//Declaramos un objeto firebaseAuth
private FirebaseAuth firebaseAuth;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //inicializamos el objeto firebaseAuth
    firebaseAuth = FirebaseAuth.getInstance();

    //Referenciamos los views
    TextEmail = (EditText) findViewById(R.id.TxtEmail);
    TextPassword = (EditText) findViewById(R.id.TxtPassword);

    btnRegistrar = (Button) findViewById(R.id.botonRegistrar);

    progressDialog = new ProgressDialog(this);

    //attaching listener to button
    btnRegistrar.setOnClickListener(this);
}

private void registrarUsuario(){

    //Obtenemos el email y la contraseña desde las cajas de texto
    String email = TextEmail.getText().toString().trim();
    String password  = TextPassword.getText().toString().trim();

    //Verificamos que las cajas de texto no esten vacías
    if(TextUtils.isEmpty(email)){
        Toast.makeText(this,"Se debe ingresar un email",Toast.LENGTH_LONG).show();
        return;
    }

    if(TextUtils.isEmpty(password)){
        Toast.makeText(this,"Falta ingresar la contraseña",Toast.LENGTH_LONG).show();
        return;
    }


    progressDialog.setMessage("Realizando registro en linea...");
    progressDialog.show();

    //creating a new user
    firebaseAuth.createUserWithEmailAndPassword(email, password)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    //checking if success
                    if(task.isSuccessful()){

                        Toast.makeText(MainActivity.this,"Se ha registrado el usuario con el email: "+ TextEmail.getText(),Toast.LENGTH_LONG).show();
                    }else{

                        Toast.makeText(MainActivity.this,"No se pudo registrar el usuario ",Toast.LENGTH_LONG).show();
                    }
                    progressDialog.dismiss();
                }
            });

}

@Override
public void onClick(View view) {
    //Invocamos al método:
    registrarUsuario();
}

I also add the files of the gradle in case I got it there at the time of introducing the services but I do not know why I followed the steps that come in the goolge documentation.

build.grade

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {

    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.google.gms:google-services:4.1.0' // google-services plugin
        classpath 'com.android.tools.build:gradle:3.2.1'


        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

app / build.grade

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.josemanuu.intento2"
        minSdkVersion 27
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'com.google.firebase:firebase-core:16.0.4'
    implementation 'com.google.firebase:firebase-auth:16.0.4'
}

apply plugin: 'com.google.gms.google-services'

Thanks for your help:)