For South America , Brazil is classified already:
South American Volleyball Confederation (CSV)
In South America, 2015 South American champions Brazil are qualified for the Women's World Championship in 2018. They will be joined by one team following a South American qualification tournament to be confirmed. The same is true for the men's teams, where 2015 South American champions Brazil will be joined by one other South America country following a qualification tournament to be confirmed.
This, to me, doesn't make sense. How come a confederation tournament from 2015 will be valid as a qualification tournament for the 2018 World Championship???
so, in reality, there is one ticket available for south America. I don't get it.