: Use a modern archive manager like WinRAR or 7-Zip . These programs are designed to recognize "split volumes" and automatically stitch them back together.
This specific filename, , appears to be a segmented archive file related to Age of Empires III: Definitive Edition (AOE III DE) . sc23847-AOEIIIDEv1329985.part04.rar
: You cannot open Part 04 by itself. You must have every preceding part (Part 01, 02, and 03) and any subsequent parts in the same folder. : Use a modern archive manager like WinRAR or 7-Zip