Campaign mode
The clock-driven default: matchdays advance on a schedule, from cadence to kickoff hour to season lifecycle.
Campaign is the default way to play. There's no live session to join: the league runs on a clock, and matchdays play out automatically on a scheduled server tick whether or not anyone's watching.
Cadence and kickoff
A league's cadence is set at creation and decides how often matchdays land. Three per week plays on Sunday, Tuesday, and Thursday. Daily plays every day. Either way, the kickoff hour is configurable, so a league can settle on a time that actually suits its managers.
League lifecycle
A campaign league moves through a fixed sequence of stages: setup, planning, preseason, active, paused, and completed. Preseason only simulates friendlies: nothing that counts toward the table happens until the league goes active.
Because the clock does the work, campaign is the mode for playing at your own pace: set your lineup and transfers before the deadline, and let the tick take it from there.