Reading the introductory paragraph to the paper, it sounds like a rehash of Kaufmann's (very good) book "At Home in the Universe", which at this point is almost 30 years old. Not sure what this paper adds, but will read it to find out.
The thesis of Kaufmann's book is that the emergence of life, given supporting conditions (variety of source chemicals in environment, sources of energy, maybe water/mixing) is all but inevitable (hence life being "at home" in the universe) rather than being some rare event.
The reasoning is that when these preconditions are met there will be a variety of chemical chain reactions occurring where the product of one reaction is used as the input to the next, and eventually reaction chains that include products that act as catalysts for parts of the reaction chain. These types of reaction can be considered as a primitive metabolism - consuming certain environmental chemicals and producing others useful to the metabolism.
From here to proto-cells and the beginning of evolution all it takes is some sort of cell-like container which (e.g.) need be nothing more than than something like froth on the seashore, based out of whatever may be floating on the water surface. Initial "reproduction" would be based on physical agitation (e.g wave action) breaking cells and creating new ones.
Different locations would have different micro-environments with different locally occurring reaction chains and "proliferation/survival of the fittest" would be the very beginning of evolution, as those reactions better able to utilize chemical sources and support their own structure/metabolism would become more widespread.
Anyway, a good book and plausible thesis in general (one could easily adapt the specifics from seashore to deep sea thermal vents etc).