@Tawne1
Have you tried calling Airbnb? I find that using their messaging system right now is very hit and miss and responses can be extremely slow or not come at all, whereas on the phone, you might be on hold for a while, but eventually you get to speak to someone. I also tried the online chat yesterday. That was quick, but the problem was then referred to another team and who knows if they will get back to me...
So, technically, if you are diagnosed with COVID-19 and can prove it, you are supposed to get a full refund. HOWEVER, I am not sure if that would apply to the full party, or just the person who is diagnosed. The Airbnb extenuating circumstances is not specific about group bookings. However, I think you have a good chance of getting Airbnb to refund you if you have evidence.