So, If I am reading it right, USA is in Group G with Australia, New Zealand, and Sweden.

There are 3 Groups, and 8 teams into the Semi-finals...

So, there are 12 teams at the olympics and 8 in the Semi finals... First and second from each group + 2 3rd place finishers?

How do they pick the 3rd place finishers ... I assume points and then goal differential, right?

Catching Sweden in our group is probably next to impossible ... so the issue is trying to make sure we overcome the -3 goal differential with respect to other teams in other groups.
Zambia is -7, and China is -5, but we are third worst with -3.