How do I implement Authenication code flow using angular-oauth2-oidc in Angular 8

I am currently following this for my oAuth2:

https://manfredsteyer.github.io/angular-oauth2-oidc/docs/index.html

I am using the authentication flow grant.

I have a main page, where users can click on the button and it gets redirect to the auth server. After users enter their credentials, it will be redirected to a temporary page, where I am suppose to use the auth code to get the access token.

I am currently stuck at the temporary page on how to get the code.

So a few questions:

1. How do i implement to get the access code and get access token?
2. How do i redirect to home page after getting access token?

-

This is how I want the flow to be like:

Prelogin -> auth server login page -> post login -> application home page

-

PreLoginComponent.ts:

export class PreLoginComponent implements OnInit {
  constructor(private oauthService: OAuthService) {}

  ngOnInit() {}

  public login() {
    this.oauthService.initCodeFlow();
  }
}

authConfig.ts:

export const authConfig: AuthConfig = {

  responseType: environment.authRequestType,

  loginUrl: environment.authServerUrl,

  redirectUri: environment.redirectUrl,

  clientId: environment.clientId,

  scope: environment.scope,

  requireHttps: false,

  showDebugInformation: true
};

PreLoginComponent.ts:

export class PreLoginComponent implements OnInit {
  constructor(private oauthService: OAuthService) {}

  ngOnInit() {}

  public login() {
    this.oauthService.initCodeFlow();
  }
}

AppComponent.ts:

import { OAuthService, JwksValidationHandler } from 'angular-oauth2-oidc';
import { authConfig } from './core/authentication/auth.config';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss']
})
export class AppComponent implements OnInit, OnDestroy {

  constructor(
    private oauthService: OAuthService
  ) {
    this.configure();
  }

  ngOnInit() {
    }

  private configure() {
    this.oauthService.configure(authConfig);
    this.oauthService.tokenValidationHandler = new JwksValidationHandler();
  }
}

PostLoginComponent.ts:

import { Component, OnInit } from '@angular/core';
import { OAuthService, JwksValidationHandler } from 'angular-oauth2-oidc';

@Component({
  selector: 'app-post-login',
  templateUrl: './post-login.component.html',
  styleUrls: ['./post-login.component.scss']
})
export class PostLoginComponent implements OnInit {
  constructor(private oauthService: OAuthService) {

  }

  ngOnInit() {
  // how do i implement to get the code and get access token 
  // how do i redirect after success
  //this.oauthService.tryLoginCodeFlow();
  }
}