From how they set up the training, I think this is a nontrivial task. Also, from a casual read through, it looks like it is generally focused on Arxiv papers.
To their credit, the authors included the models used and the metrics they used to validate their model. They also have detailed notes on the architecture for training which, at a quick glance, doesn't look easy to replicate unless you can borrow some GPU's in the cloud.
It focused on arxiv because you need a large set of labelled data (i.e. long documents with summaries). There is not many datasets of that kind out there.
To their credit, the authors included the models used and the metrics they used to validate their model. They also have detailed notes on the architecture for training which, at a quick glance, doesn't look easy to replicate unless you can borrow some GPU's in the cloud.