Hi Vicki,
The Register block or shortcode is the right one.
When a user goes to a page with that on….
1) If they are not logged in they will be asked for an email address to start the login/register process
2) If the email is recognised, they get a login form
3) If the email is not recognised, they get a register form
4) If they are already logged in and in the directory – they will get a page like your screenshot (colours are way different to default!)
Hope that helps.
Your theme style sheet has made it look a little weird though colour wise and no borders.