If the RAR file contains raw folders (like def or vehicle ), you must repackage them correctly. and files inside the extracted RAR.
You need a reliable archiver. Do not use online "RAR to ZIP" converters for large mods; use desktop software. rar to scs file converter
SimCity 4 .scs (SimCity Save) is actually a container: If the RAR file contains raw folders (like
To summarize the correct workflow: