What’s your code look like so far for saving/loading the actors placed in the world? If you’re not already doing so, you’ll want to get all the actors of class, let’s say (PlaceablesBP) and using a for each loop add the world transform of each actor to a transform array that you’ll want to save.
Then on load you’ll want to cycle through the transform array using a For Each Loop and spawn the PlaceableBP actor at the transform loaded in the array.