I'm not an expert or anything, but I've read in various posts the Brazil consulate in Rio doesn't send any information.
I'll recommend your Fiancee to just go ahead and fill out the DS-160 form, do the payment, then pick the interview date.
I'll attached a form I found to be very helpful.
I'm still waiting for my case to be received by the NVC, so you're ahead of me by 2 months 😄.