When I go to WordPress.org to enter the info for username etc, at the bottom of the page it wants me to install . . .
When I did my installations with SimpleScripts at the server, SimpleScripts sent my login credentials to me. So if the credentials you have are from whoever did your installation and are not working, I would contact the installer (the server folks) and ask what might be wrong. But if you are trying to use those credentials at wordpress.org, try going to your site address instead. WordPress.com sites have logins at wordpress.com, but self-hosted sites do not login at wordpress.org...and the confusing part in all of that can be that the login pages all look the same even though they go to very different places.