When setting up a playlist, there is a screen to assign the playlist to multiple classes/groups at once that ALSO has assign dates and due dates.

These assign dates and due dates will change the assign/due date for all activties and quizzes inside the playlist at once (should you choose to do that). It does NOT mean you can schedule that playlist to appear on the "assigned" date.

Scheduling a playlist to appear is against CBE strategy, as want learners to have agency over their own learning, and not be beholden to the teacher to tell them when they are "ready" to learn.