Usually, a central user management like a Single-Sign-On (SSO) is a part deployed into the process application landscape. This is responsible for authentication and authorization of the user and is required to control the role-based access to user tasks.
In our example application, we disable any security checks to avoid the unneeded complexity. In doing so, we implemented a trivial user store holding some pre-defined users used in example components and allow to simply switch users from the frontend by choosing a different user from the drop-down list.
It is integrated with the example frontends by passing around the user id along with the requests and provide a way to resolve the user by that id. Technically speaking, the user id can be used to retrieve the permissions of the user and check them in the backend.