Well CB installs fine and you can register one user after you install it. The two problems are

1. The new user does not show up in user management.

2. I looked at the user table in the data base and the above user that was registered has a User_id of 0 and every time you try to register a new user I believe it tries to register with the User_id of 0 therefore creating a failed store duplicate error

Please I need help

If you have access to your database, you can find the user id in th relevant table and change it to autoincrement. Start off with a base above existing accounts.

Probably an installation hiccup, but this should resolve it for you