Local co-op and split screen

There is no split-screen mode, couch co-op profile, or second-player prompt. PlayStation's store page identifies one offline player, and Steam lists only Single-player. A second person can help choose moves or pass the controller, but the game treats that as one save and one player.

Online co-op and shared campaigns

Zero Company has no invitation lobby, drop-in squad slot, shared campaign host, or asynchronous turn exchange. Every Operator in a tactical mission belongs to the same commander, including the custom recruits and named story characters. Cloud saves can move one player's save between supported devices; they do not create a shared campaign.

Why four Operators does not mean four players

Most missions allow a squad of four Operators. That number is a deployment limit, not a co-op player count. One player spends the Action Points for all four, chooses their abilities, and manages their equipment and Bonds between missions.

For the solo campaign loop, read Is STAR WARS Zero Company single-player?. The multiplayer page separately covers PvP and network modes.