They don't provide any definition for active, that's why I say it's meaningless marketing smoke and mirrors.
It makes a big difference whether you define an active user as "has logged in during the last 90 days" versus "last 30 days" or "has a record in our database".
I have no problems believing that they're approaching 1mio registrations/day. But as said, that's a meaningless figure. What I'd really like to know is their churn/retention.
It also says the US has over 70 million active users.
Read the article.