The first node ( add instanced static mesh component ), sort of gets the system ready. You will not see anything at this point.
The second node ( add instance world space, which does the main work ) will make your meshes appear, but they will actually be copies of the one main instanced mesh from the first node.
Imagine you magically had all the coordinates of you current stuff in an array, you could say
To get ready to add loads of cubes, and then
To actually put them in the level.
As far as getting all the information you need, meh, you’ve got your work cut out. Probably need to write a blueprint to put all the transforms ( location, rotation etc ) in the array, before you can place the meshes.
Also, notice this is a static mesh COMPONENT. That means this is all part of a blueprint, not the level blueprint.