If you copy the entire folder that contains the clone into the VirtualBox VM directory on the destination machine, you don't need to create a new VM and point it at the associated .vdi since it also has the configuration settings for the VM in the .vbox file. Move the entire folder for your third step and fire up VirtualBox on the desintation machine. It will already see the new (cloned) VM in the folder and populate the list of available VMs appropriately.