How do I copy files from the VM to the phone’s storage?
When the phone is connected to the vm, it does not appear as a usb memory.
It will probably work as MTP device (I presume Android phone). You should connect phone, select files/storage mode on it, and in sys-usb it will be available in file manager (e.g. Dolphin).
Copying files from other VMs to sys-usb and back should be done in a usual way (qvm-copy or gui shortcuts).