You will need to verify your account with Last.fm to check whether or not you have access to the beta.
 Verify with Last.fm here. It uses the Last.fm API, not a password, so all you have to do is click a button.

Please note, this only checks to see if you have beta access and then grants it.
If you have not at least joined the group on Last.fm, then there is likely no chance that you will have access, unless you have spoken directly with me.