This 45GB mega folder consists of all the cracking tools you can think of from creating proxies, checking proxies, getting combo leaks, verifying leaks, and at last checkers to see which accounts are working
These tools may/may not contain viruses so install them in VM or sandbox. These tools are used for cracking (creating combos, proxies, checking proxies, and checkers which take the combos you provided in the format of email:pass or something like that and then execute the login and see if the combo you provided is correct or not).
Attackers on mega.nz might attempt to trick you into installing programs that harm your browsing experience (for example, by changing your homepage or showing extra ads on sites you visit)
Its not asking for any decryption key I tried just now check once again Google shows harmful site warning click learn more and then view this site. After that mega isnt asking for any key