Virtualbox: how do I copy-n-paste from host to guest’s CLI?

I am running an Ubuntu server guest in Virtualbox(latest version). Windows 10 is the host. Bidirectional drag-n-drop and clipboard enabled. When I copy into the guest, nothing happens. I receive this error message when using drag-n-drop:

DnD: Error: Drag and drop to guest not possible — either the guest OS does not support this, or the Guest Additions are not installed

The guest is CLI only, no GUI or desktop environment. Could that be an issue with drag-n-drop and copy-n-paste? Guest additions are installed.