I am new to JWT authentication. I can use the default Admin credentials for accessing the API's. Where most of them use, but I don't how to register and add a user within the application.
Do someone have a postman collections or can someone help to with the flow?
After you login to Gateway web application as an admin user,
Option 1 [What OP wants]
Go to Administration -> API Menu which will bring you to the swagger documentation page and then select the default definition on the top right drop down. The 'user-resource' section should have all the Rest end points you are looking for with its definitions. Sample curl from this page for user creation,
Using this page you should be able to get all that you need.
Option 2
Go to Administration -> User Management Menu on the top right and you should be able to add/update/delete users.
See this video @1:45 video link