In this guide, the process of building a Next.js application integrated with PropelAuth and Supabase is detailed, focusing on managing users and organizations. The guide begins with setting up PropelAuth for authentication by creating a project and configuring authentication methods, followed by establishing a Supabase project with a database table. It outlines the steps to create and configure a Next.js application, including the installation of necessary libraries and environment variables. The guide explains setting up routes and middleware for authentication, creating a Supabase client to use user information from PropelAuth, and implementing row-level security (RLS) to ensure data access control. Additionally, it discusses the use of PropelAuth for enabling B2B authentication features like organizations and role-based access control, explaining how to manage organizational data within Supabase. The guide emphasizes the ease of implementing authentication features without the need for custom UI development, offering a streamlined approach to building authentication frameworks in applications.