In the Game Options tab found in the Instructions is this.
To play a team game, try doubles, triples and quadruples. Quadruples games must be played with 8 players 8 or 12 players, triples games with 6 players 6 or 9 or 12, doubles games with 4 or 6 or 8 4 or 6 or 8 or 10 or 12. Teammates are determined by the sequence of players, for example the first two players and second two players make up two teams in a doubles game. In team games, you can deploy on your teammate's regions and reinforce to your teammate's adjacent regions (but not through them). The score is calculated per team. When a player is auto-kicked in a team game, the first surviving teammate inherits the troops and spoils. In team games, zone bonuses must be held by a single player to have effect.