Quick answer: STAR WARS Zero Company is single-player only. EA explicitly says it does not include online/competitive multiplayer, online co-op, local co-op, split-screen co-op or other online social play features.
Why the squad gameplay is still single-player
You command several Operators during tactical missions, but one player controls the squad. Terms such as "team," "squad" and "Call for Backup" describe in-game mechanics, not a second human joining the mission.
No online co-op
There is no official mode where another player controls part of Zero Company over the internet. If you are buying specifically to play a tactics campaign with a friend, the launch version does not provide that feature.
No local or split-screen co-op
EA's platform guide also rules out local and split-screen co-op. The console versions remain a single-player experience even if multiple controllers are connected.
Does single-player require always-online access?
EA says an online connection is not part of the PC system requirements because the game is single-player. Internet access can still be needed for downloading, installing updates or using storefront/platform features.
Could multiplayer be added later?
EA has not announced it. A status page should not turn "not included now" into a prediction. If post-launch plans change, this page can be updated from official patch notes or announcements.
Can you share tactics with friends?
You can still share builds, screenshots, mission stories and strategy through Steam Community or the official EA Star Wars Discord, but those community spaces do not add networked control to the campaign. One player makes the squad's tactical and strategic decisions. The absence of co-op also means there is no matchmaking population to consider when deciding whether the game is still playable years later; the core campaign is designed around solo play.
Who this mode is designed for
Zero Company is structured as a solo campaign in which one player controls both the tactical squad and strategic decisions at the Den. That design matters because pausing to inspect abilities, planning a full squad turn, deciding which Operation to pursue and accepting campaign consequences are all paced around one decision-maker. There is no second-player progression track, shared save, host/client system or drop-in role advertised by EA.
For buyers comparing editions, multiplayer status also does not change between Standard and Deluxe. Deluxe adds cosmetic content; it does not unlock co-op or competitive modes.