Special1151_pack4.part2.rar -

: You are missing one of the parts (like Part 1 or Part 3) in that folder.

: Unpacks the files directly into your current folder. SPECIAL1151_PACK4.part2.rar

You do need to extract each part individually. The software is designed to automatically "stitch" them back together. : You are missing one of the parts

: One of the parts was likely corrupted during download. You may need to redownload the specific part mentioned in the error message. SPECIAL1151_PACK4.part2.rar

You need a file archiver that supports the .rar format. Popular free and paid options include: : The native tool for .rar files.