qBittorrent creates a subdirectory using the path string in the torrent itself. But this sometimes causes problems. For example, on Linux, you can create a directory that has ':' in its name, but not on Windows. So, if the qBittorrent creates a subdirectory whose name contains ':' on Linux, this path is inaccessible from Windows.
So, does qBit have a preference that allows the user to specify some specific forbidden characters when creating a subdirectory for a torrent? Those forbidden characters could be just omitted (like "ab:cd" becomes "abcd") or replaced with an underscore (like "ab:cd" becomes "ab_cd").