According to the rules:
" If multiple players tie for the highest card, then the next player in clockwise order from the current start player takes the box and is the new start player."
They are only talking about the players who tied for the highest card. So when they mention "players", it is refering to these people and not everyone else in the game. So player 2 is not included in this reference to "players".
So Player 3 would be the next player in clockwise order from the current start player.