You cannot use part03.rar by itself. You must download all parts of the set (e.g., if there are 10 parts, you need all 10) for the extraction to work.
These downloads are typically "cracked" or pirated versions of the game, which is illegal and violates copyright laws. Recommended Safe Alternative download-the-sims-apun-kagames-part03-rar
The file download-the-sims-apun-kagames-part03-rar is the third segment of a multi-part compressed archive for a version of The Sims hosted on the third-party website . Understanding Multi-Part Files You cannot use part03