No, pg 17 of the rule book, Act II ends with 3 closed sets, and 2 ready characters after paying your dues. Act III ends with 3 closed sets and 3 ready characters after dues (pg 25).
The rule book doesn't seem to agree with this.
For the 3 player game it says "The first player to Pay their Dues while having 2 closed sets and 2 ready characters wins at the 3 player game. A 3 player game can be played at any Act (My bold)
My understanding of the above is that for the 3 player game, the end condition stated above will always apply, whatever the Act.