The built-in JWT server will authenticate the user credentials passed from the application client, by validating against users defined in a file or in a database. You can easily implement this by using the authentication template.
Note
The authentication template will be restored if the "Auth Template" option is changed and the PowerServer C# solution is re-built from the PowerBuilder IDE. Therefore, do not change the "Auth Template" option if you have made changes to the template in the solution (otherwise changes will be lost).