Use a program like WinRAR or 7-Zip to right-click on part01.rar and select "Extract Here." The software will automatically pull data from part09 and all other segments to recreate the full installer or game folder [1, 4].

Ensure you have every single file in the sequence (part01, part02, etc.) in the same folder [1, 2].

If you are trying to "develop" or modify the game files within that archive, you will first need to complete the extraction above before using tools like Sims 4 Studio to access the internal packages.