Do you really, REALLY want to open that Pandora's Box? Here's why you're not going to get the answer you want.
1) You're OBVIOUSLY attempting something illegal here by pirating a game... -- Password Protected Archives are common for Warez downloads to restrict proper distribution by pirates.
2) You're OBVIOUSLY foolish to think that GTA VI is already available... -- Rockstar Games is still developing GTA VI & major gamers are EXTREMELY PROTECTIVE with majorly beloved franchises when it comes to stolen in-dev leaks & will go after the hackers in order to save the game from being canceled.
3) You're OBVIOUSLY foolish to think there's no unwanted "extras"... -- With the above-mentioned notes, what you downloaded is very likely a trollish package that's very likely filled with unwanted "extras" (like viruses, malware, spyware, ransomware & all other unwanted forms of "-ware") locked inside that would likely brick your computer in some form within minutes (possibly hours or days, if they're more subversive).
You should just delete that archive & wait patiently like everybody else for any official announcements for GTA VI... otherwise, you'll justly deserve all the evils that may inflict your computer by unlocking that archive.