Ensure you aren't missing "part01.rar" or "part02.rar," as the extraction cannot begin without the first volume.
As of October 2022, the official Sims 4 Base Game is completely free to play on EA App, Steam, and consoles.
This is the third part of a multi-part compressed folder. To extract the game, you must have all parts (part01, part02, etc.) in the same folder and use a program like WinRAR or 7-Zip to extract the first one.
Downloaded "All-in-One" packs from unofficial sources frequently carry risks of malware or outdated "cracks" that can cause the game to crash or fail to save.