elgg.org account registration -- where is it?

Apologies if this was covered elsewhere -- I didn't see it when I searched.

Where is the account registration for this site?  I directed a colleague here to register so she can ask some technical questions, and she said she couldn't find anywhere to register.  I just checked and couldn't find it either.  I only saw options to log in with an existing account, log in with a Twitter account, or retrieve a lost password for an existing account.

I'm posting from an account I created quite a while ago, so I know it was possible to register an account at some time.  Are old accounts grandfathered, and only Twitter logins are now possible for new accounts?

Thank you!