How to check what license and what role a user has been assigned in RTC & RTC-RQM integrated Tools? I need the steps. This is about an environment where in the web server us administered by a centralized team.

Go to 'Manage Lifecycle Projects', then 'Members' menu (typically https://jazz-server:9443/admin/web/members).
That provides you with the list of all members of a given Lifecycle Project, and their 'belonging' to CCM (RTC) and/or QM (RQM) and/or RM (RRC).
If you then click on 'Show Member Details', this will show you the 'Process Roles' of the member in CCM, QM and RM.

As for the licenses details, you can either:
- go to the 'Jazz Team Server home'-'Active Users', click a user and see 'Client Access Licenses'
- go to 'Jazz Team Server home'-'Client Access License Management', select a CAL key, and see which users are assigned this CAL.