I have tried many different ways to configure the settings for Layout > Tree > Directed but I never manage to obtain the layout as you provided in the file sample.graphml:
The closes I manage to get to the layout is by using layout style 'compact'.
1. How do you get to have the edges to start from the bottom left of the nodes instead of the center?
2. How do you get to stack the nodes more frequently? For instance, see 'Creation Information' at the bottom: the original sample file shows the 'RelatedMaterial' nodes on top of each other, instead of side by side like in my attempt.