A huge range of writers feature in this. There are those such as Thomas Pynchon or the Peruvian poet Emilio Adolfo Westphalen, who went for many years without writing. There are unknown figures who never wrote at all. And there are those who contributed ideas, such as Wittgenstein's "whereof one cannot speak, thereof one must be silent".
There is structure to the overall work, which is clearly not a collection of actual footnotes. But the links are loose and there is a lot of indirection, such as a correspondent mentioning an author whose character illustrates some aspect of not writing. And Vila-Matas disconcertingly mixes in some fictional material: he invents a character Clement Cadou, for example, who meets the Polish poet Witold Gombrowicz as a child and is written about by Georges Perec.
The frame around this involves a writer — at least of footnotes — who intrudes himself into his commentary. There isn't a narrative in this, but we learn scattered personal details. He is humpbacked, likes the music of Chet Baker, wrote a novel a long time ago, corresponds with others who provide him with leads, and eventually loses his job.
Bartleby & Co. is amusing and thought provoking, but it is very much a literary work, full of ideas and connections whose full appeal depends on familiarity with the history of Western literature. It's not something that will have mass appeal.