Unofficial "free download" sites are notorious for bundling malware, miners, or adware with game files.
While the "Civil War Edition" bundle is often advertised for free on various platforms, there are several reasons to be cautious: Victoria II: Civil War Edition Free Download
If you are looking for the best way to play the "Civil War" content, look for the on official storefronts. Unofficial "free download" sites are notorious for bundling