With the League Manager, a schedule is required to enter scores. It also is used to control matchups, in the case of leagues who play some form of match play, sub requests and the ability to print scorecards. There are three main ways to create schedules, all available in:
League Setup -> Step 7 Scheduling
This is the most common way is to use the Auto Generate Schedule Feature as shown in this help video:
When you auto generate a schedule, all players/teams are scheduled for the rounds you select. In match play leagues, it will optimize the schedule so that each player/team plays each player/team an equal number of times as possible.
Note that if you only schedule a portion of the season, or manually set 1 or more rounds and auto schedule the rest, repeat matchups are almost certain to occur.
This feature allows you to manually set matchups in the schedule, or change which course/side you're playing for a given round. You choose the round, then you choose which player or team plays in each group. You can also edit a previously created schedule. This option is more popular with leagues who typically only have a subset of players playing any given week. If you play match play, do NOT remove players from the schedule
Moving Groups Up and Down on the Tee Sheet
While editing a schedule for a single round, you can drag pairings up and down in the order to change which group they are playing in.
For leagues who only have a subset of players playing any given week, this feature allows you to choose which players are playing, and then the foursomes are generated by Golf League Tracker, in an attempt to spread out pairings as much as possible.