Very useful utility for managing files.
StuffIt Archive Manager organizes your archives into collections.
Utility to split and join files using several common cross-platform formats (Mac, Unix, Windows), such as hjsplit, hacha, fastsplit or winsplit.
The app errors
As for the question, it is related to software and specifically asks why the program "Split&Concat" does not work on Mac OS Big Sur and gives an error. Unfortunately, without further information, it is difficult to provide a specific answer. It is recommended to ensure that the program is compatible with Mac OS Big Sur by checking for any updates or contacting the developer for support.