The idea is simply that a complete scene contains some kind of activity, a situation, a manner of thinking, and an attitude.
To quote the storymind article How Scenes Relate to Dramatica's Story Elements:
I think the term Event can be a bit misleading though; for example, the entire scene may take place while driving in a car, which is that scene's Activity. In that case the Activity isn't something that happens at one single point during the scene, but throughout.
Anyway, this doesn't have to tie to the rest of the structure at all. There's no particular relationship between the throughline domains and the scene Events.
Of course, many of your scenes will have things that ties to the structure -- for example, the Activity of climbing the Cliffs of Despair in The Princess Bride certainly represents Westley's IC Issue of Attempt as he impacts everyone by attempting that.
If you want to delve into it further I find these narrative first articles useful. Jim calls this component of scene structure TKAD (because of how Fixed Attitude, Situation, Activity, and Mentality map to Thought, Knowledge, Abiltity, and Desire):