You must purchase the game. Rockstar has released several versions. The best one for Windows 10 is the Rockstar Launcher version or the definitive edition (with caveats).
Once the download is complete, follow these steps to install the game: Gta San Andreas Pc Download Windows 10
Some users may experience compatibility issues with Grand Theft Auto: San Andreas on Windows 10. If you encounter any issues, try the following: You must purchase the game
The provides several modern technical upgrades for Windows 10 users: Gta San Andreas Pc Download Windows 10