Use software like WinRAR or 7-Zip. Right-click on Part 1 and select "Extract Here." This will automatically pull data from Part 2, Part 3, and so on to create one complete game folder.
You cannot install the game with just part2.rar . You must download every part listed on the ApunKaGames download page. download-need-for-speed-payback-apun-kagames-part2-rar
Once installed, launch the game using the NeedForSpeedPayback icon in the installation directory. Use software like WinRAR or 7-Zip
For a visual walkthrough on how to navigate the site's download process and handle multi-part files: find the Setup.exe file
Place all downloaded .rar parts into the same folder on your computer.
Open the newly created folder, find the Setup.exe file, and follow the installation instructions.