Apparently z-library received user donations and at some point used that donated money to make purchases intended to promote the carrying on of unlawful activities, probably buying hardware or services relating to the operation of z-library, which qualifies as money laundering. Even though it doesn't fit the normal conception of money laundering (hiding the source of illegal money) it still falls under the same law.
> In or about and between January 2018 and November 2022, both dates being approximate and inclusive, within the Eastern District of New York and elsewhere, the defendants ANTON NAPOLSKY, also known as "Anton Napolskiy," and VALERJIA ERMAKOVA, together with others, did knowingly and intentionally conspire to conduct one or more financial transactions in and affecting interstate and foreign commerce, to wit: deposits, withdrawals and transfers of funds and monetary instruments, which transactions in fact involved the proceeds of specified unlawful activity, to wit: criminal copyright, as alleged in Count One, in violation of Title 17, United States Code, Section 506(a)(1)(A), and wire fraud, as alleged in Counts Three and Four, in violation of Title 18, United States Code, Section 1343 (collectively, the "Specified Unlawful Activities"), knowing that the property involved in the transactions represented the proceeds of some form of unlawful activity, with intent to promote the carrying on of the Specified Unlawful Activities, contrary to Title 18, United States Code, Section 1956(a)(l)(A)(i).
https://torrentfreak.com/images/z_library_indictment_0.pdf
> In or about and between January 2018 and November 2022, both dates being approximate and inclusive, within the Eastern District of New York and elsewhere, the defendants ANTON NAPOLSKY, also known as "Anton Napolskiy," and VALERJIA ERMAKOVA, together with others, did knowingly and intentionally conspire to conduct one or more financial transactions in and affecting interstate and foreign commerce, to wit: deposits, withdrawals and transfers of funds and monetary instruments, which transactions in fact involved the proceeds of specified unlawful activity, to wit: criminal copyright, as alleged in Count One, in violation of Title 17, United States Code, Section 506(a)(1)(A), and wire fraud, as alleged in Counts Three and Four, in violation of Title 18, United States Code, Section 1343 (collectively, the "Specified Unlawful Activities"), knowing that the property involved in the transactions represented the proceeds of some form of unlawful activity, with intent to promote the carrying on of the Specified Unlawful Activities, contrary to Title 18, United States Code, Section 1956(a)(l)(A)(i).
https://torrentfreak.com/images/z_library_indictment_0.pdf