If you are an adult with a job, just buy the game on sale for $15. The peace of mind and access to GTA Online (which is half the fun) is worth infinitely more than the hassle of malware cleanup.

Compression involves removing non-essential data or using advanced algorithms to shrink file sizes.

If budget is tight: (Steam/Rockstar/Epic). GTA 5 is frequently under $15, and it's far cheaper than cleaning a malware infection or replacing stolen accounts.

Never run a file named "Setup.exe" that is under 1GB. If your antivirus screams, listen to it.