One week and no answer?
I must not be paying attention, because I've never noticed the ambassador tag. Our "featured member" has been the featured member for years, I don't think they ever update the featured member.
I would imagine that to be an ambassador, you would have to be active here, helping people, and juicing as well. You probably also need to toe the line, so to speak, and basically support and promote all of the official advice, suggestions, and juice regimens and plans.
I've been active here for a few years, but frequently find myself disagreeing with some of the things promoted here, which is why I'll probably never be an Ambassador LOL!