The current pre-release of the client ("pioneer" in the version) is only compatible to itself. So you can only play with other testers. Please be aware!
We certainly need to have more info on this? What does it say if you log in? Does it give an error? Provide the client log. Have you linked your account to Steam?
@Brutus5000 that's why I want a how to get started so I can link him that FAQ post....