Alpha 2 is still live but is no longer used by the latest browser, and you no longer use the browser to log in.
Instead you need the safe_auth authenticator which is a command line tool. This is now used for login, as well as creating an account, and for authorising apps which request access to your SAFE storage. So no more authentication request popups in the browser - instead they appear in the terminal where you ran safe_auth.
Note though, that safe_auth is being rolled into the SAFE command line interface command safe, so when that happens safe_auth will no longer be used, but for now that is what is used to login!
The above is announced in the following Dev update, which includes links to other posts explaining how to use these tools. All the tools have been updated since then though, so make sure you get the latest releases.
It’s a good time to come back because things are moving fast. Enjoy!