CCC will only back up system files to or from locally-attached macOS-formatted filesystems Please note that network volumes mounted by third-party software is generally not supportable. You can mount network volumes in the Finder, or via the Mount a network volume. In general, you can reasonably expect to back up user data - files that belong to your user account - to and from non-macOS-formatted volumes.
However, these filesystems offer limited support for macOS-filesystem features, so special consideration must be given when backing up to these volumes. Non-macOS-formatted volumes are presented in CCC's Source and Destination selectors in the same manner as macOS-formatted volumes, so there are no special steps required for backing up to or from these filesystems. AFP and SMB via macOS and Windows File Sharing) and to other non-macOS-formatted volumes such as FAT32. In addition to backing up to volumes formatted with the macOS standard HFS+ or APFS format (collectively referred to as 'macOS-formatted' from here forward), CCC can copy user data files to network volumes (e.g.