When setting up a Remote Sync, a warning message saying A conflicting <type> behavior exists at /path/to/folder/ indicates that you are attempting to set up the sync on a prohibited folder.

Check that the folder contains no Remote Mounts or that a duplicate sync doesn't already exist.

For folders which contain Remote Mounts, you can instead set up individual syncs for each of the subfolders that contain no Remote Mounts within them.

Alternatively, see if Automations, which can be used with Remote Mount folders, are a better fit for your move or copy needs.