I received an email today, I don't think it's account specific. Just log into the app, check the rewards section, and it should be there waiting for you. It says it works on existing accounts too, which is always a bonus.
I haven't signed up for it myself yet as I've still got a month left on a Deezer trial at the mo, so I'm going to wait for that to run out and hope this is still available then. If anyone else gives it a go though and could let us know if it does work on existing accounts that would be muchly appreciated