While you may find links claiming to compress a 60GB game into 5MB or 100MB, Legitimate compression can significantly reduce file size, but it cannot violate the laws of data physics. Re-encoding high-definition textures and audio files has limits. A "highly compressed" download of MGS V usually involves removing multi-language voiceovers (keeping only English) and compressing texture files, which can save significant space.
Installing a highly compressed version is straightforward. First, download the setup files from a reputable source. Disable your antivirus temporarily, as many compression tools can trigger false positives. Run the installer and wait for the decompression process to finish; this may take anywhere from 30 minutes to two hours depending on your CPU speed. Once finished, you can re-enable your antivirus and launch the game from the desktop shortcut. While you may find links claiming to compress