Z-Library is definitely what you need, but there’s still no dedicated community on Lemmy that I know of. You’ll find all that you need to access it in Reddit (r/zlibrary). Anna’s Archive is also very good, but sometimes the latest releases aren’t found there, while they are on Z-Lib
That’s what I like about E-books, this isn’t even an issue. I only buy physical copies for books that I specifically want to own in such format, in which obviously I won’t write or underline anything.