As this paper is from 2015 and I can't claim to understand it, is the follow up paper by the first author [0] the reason why it actually doesn't work?
the electrode setup was a concentric ring setup so it was simpler than a spherical setup like a fusor kind of device
https://en.wikipedia.org/wiki/Fusor
https://en.wikipedia.org/wiki/Polywell
the most common fusion concepts nowadays involve magnetic enclosure and or compression, of plasma, and electric charge based acceleration of the plasma.