Sorry I just saw this; good question. When "cloud to cloud" (even with the same credentials inside the same bucket in both panes) my "Copy" and "Move" menu items are both grayed out. I also can't drag and drop as I can in Windows. But when I have my Mac's local drive in one of the two panes then it does allow me to copy and move items.
My primary concern is being able to copy and move "cloud to cloud" as I can in Windows.

Using the same S3 credentials with Cloudberry Explorer on my Windows desktop I can move and copy files between the two panes. But with MSP360 (CloudBerry) Explorer on my Macbook the copy and move functionality is not available; both are grayed out in the File and right-click menus (see attached screenshot). I've tried to submit a support ticket but when I select "freeware" it won't allow me to. I've searched these forums and used Google to no avail.
This doesn't seem to be very useful without basic copy and move functionality.