Maggie Brewster's guide from August 3, 2023, details the process of creating a simple web application that uses Pivot's new embedding features to display different charts for each user selected from a dropdown menu. The application is built with React and Express, utilizing create-react-app to set up a basic React app with TypeScript and BlueprintJS for UI components. It includes a UsersMenu component to simulate user switching, where each user has specific access filters for data visualization. The backend involves an Express server that signs embed links based on user filters, using cryptographic signing to ensure secure access. A function fetches these signed links, which are then displayed in an iframe, dynamically updating whenever a user is selected or logged in, showcasing the integration of frontend and backend processes to deliver personalized data visualizations.