I clicked the @30sleeps username below the girl's image and I was redirected to a Twitter authorization request. That's a little shady IMHO. Now I'm not so sure

I clicked the @30sleeps username below the girl's image and I was redirected to a Twitter authorization request. That's a little shady IMHO. Now I'm not so sure about signing up. What happens when I click the big signup button? E.g. will my girlfriend or somebody I know be able to see I clicked the button? Are you planning to match people u according to things they like to talk about and who they follow?