If you use JSON web tokens to authenticate users in your Angular app, then you need to send those tokens to the server with every request. Fortunately, you can do that easily with an HTTP Interceptor.
If you've got an Angular app that relies on Spring Boot to do the heavy-lifting on the back-end side, then you're probably going to need some kind of login solution. Fortunately, you can do that with a JSON Web Token (JWT).