Hi Palani -
Tableau should have launched a browser right after install completed to have you create your admin account.UNLESS you are installing Server on the same machine that you have previously run Tableau Server. If that is the case, use the old admin account/password - Tableau still remembers it.
As I recall (I could be wrong), you should continue to be redirected to that "create a login" page until the admin account is on the server.
My advice would be not to waste a lot of time trying to troubleshoot this - just uninstall, make sure you've deleted all the "old" information on the system using this article, and re-install. Should take you no more than 15 minutes.
Thanks for your quick response.