USB drive is set up and shows on my netwwork when I sign in to My-share. Problem I am having is trying to add files or folders (MacOS). I get a dialog box, Modifying My-share requires an administrator

I've just started running my AX1800 as a Mac Time Machine. Performance is OK, but I doubt that it's optimal. I'm using a USB3-attached 4TB drive. I formatted it as HFS+, which I suspect isn't native t