CUSA is the only other conference playing.
CUSA isn't really playing either. League members Kentucky, South Carolina and UAB are playing some games, some against each other, some against non-conference team (including several games against ACC opponents). But the rest of the conference is not playing now, they are waiting until the spring.
The Sun Belt is also playing now, but they only have four men's soccer playing schools.
I am pretty sure this is the whole list:
Pitt, Louisville, Virginia, Virginia Tech, Notre Dame, Syracuse, Wake, North Carolina, Duke, Clemson, NC State, Kentucky, South Carolina, UAB, Mercer, Georgia State, Georgia Southern, Central Arkansas and Coastal Carolina. Also, Navy was supposed to play Syracuse and has a game scheduled against NC State coming up, but it looks like that's the only games they were supposed to play this fall, so I don't think they count. There might be one or two other schools that are planning on doing that, but if there are the number is small.
That's the reason why the poll only has five teams in it. There are only around 19 schools playing this fall.