If you have part 1, 2, and 4, the software would highlight part 3 in red, indicating a "continuity gap" before you even try to open the archive.
Large games like Far Cry 6 often exceed 60GB-100GB. When split into 2GB or 5GB parts, the most common point of failure for users is a single "bad" part that ruins the whole installation. This feature solves that "needle in a haystack" problem.
If the file is identified as corrupt or the wrong size, it automatically triggers a re-download of just that specific segment from an alternative mirror, saving you from having to restart the entire multi-gigabyte process.
As soon as a single part (like .part03.rar ) finishes downloading, the system automatically runs a checksum (MD5/SHA-1) against a manifest file.