Collections #2-5 contains 2.2 billion usernames and passwords and includes 845GB of stolen data. The data includes 25 billion records but according to researchers most of the leaked accounts are duplicated. Researchers believe that the hackers might have collected the data from many low-key websites. Instead of selling the data on underground forums like the dark web, the hackers behind the Collections data leak are offering such a massive number of unique credentials and emails IDs online for free. The databases can be accessed easily as a Mega upload link as well as on different hacking forums.
Source: https://www.hackread.com/worlds-largest-data-dump-surfaces-with-2-2-billion-accounts/