No, it's not a scam or phishing, they need your email just because they want to apprise you everytime a payment is realized and credited on your account, by other participants. You know always what's happening. And if you're signing up and, exactly in that moment, the power line of Internet falls down, for any reasons, you don't lose anything because they send you the password that you need to go on, in case you interrupt the signing up.
I have decided to participate 2 weeks ago and it's working all good. I'm satisfied.