To reduce the file size from 4.7 GB down to 600 MB, certain non-essential assets are usually modified:
Do not try to run the game directly from the zipped folder. Right-click the downloaded 600 MB archive and select "Extract Here" or "Extract to GTA San Andreas" using WinRAR or 7-Zip. Step 3: Run the Setup or Direct Executable Gta San Andreas 600 Mb Download Pc Mediafire