If I remember correctly, actual pirated copies would have been maybe tens of megabytes, since they didn't include the CD audio. But that would still have been a hefty modem download.
People were still replacing their 14.4k modems with 28.8s in 1996. I remember seeing the Quake 15 x 1.44 zips on local BBSes, which would've taken at least 3.5 hours over a perfect 14.4 connection so definitely a daunting phone line tie-up for the average kid (I had the CD.)
The common pirated version of Quake was a 20MB pre-release leak that had oodles and oodles of minor differences to the final version. All of the actual levels themselves are playable and completable. The funniest differences are a mean trap that was removed from the final E1M1, and E2M6 still begins with the eponymous oubliette, banished from official releases until 2021 (!).
That's why you had a download manager and left the machine running all night.
I got 3kB/sec, or 6 minutes per meg in ‘96. 10 meg an hour wasn’t terrible even I. The U.K. where you paid a penny a minute.