Spring Boot is frequently used for business applications conjunction with Angular, with Spring Boot providing REST API endpoints and an Angular app delivering a user front-end on top of those endpoints.
To help you get started with that kind of setup, particularly when it comes to the subjects of authentication and authorization and how to keep user data secure between the components involved in such an architecture, these GitHub projects can be quite helpful. All of those support the most recent versions of Spring Boot, Spring Security, and Angular (3, 6, and 15, respectively):