How do you use the top section of the repeater?

[Boldline]

Is there a special way to use the top section of the repeater panel?

[VectorStyler]

@Boldline Yes, when that button is clicked, it will list symbols that can be added to the repeated set of objects.
The easiest way to have symbols in a document is to set names to objects and set the "Symbol" role (Role button in Object Options).