If you want to use the Shared Folders feature with VirtualBox, you must first install guest additions. Installation method: The top menu bar->devices->install Guest Additions.
After clicking Install, VirtualBox will eject the existing ISO file in the virtual CD-ROM, load the Vboxguestadditions.iso, and then run it.
Add an optical drive to the storage tree and use it to load the vboxguestadditions.iso. Set Ubuntu ISO as the first IDE controller main channel, Vboxguestadditions.iso set to slave channel.
Select shared folder: Share ask price clip name is share
Then go into the Ubuntu system in the virtual machine, open the terminal and enter
Cd/mnt
mkdir Ubutushare
Execution: sudo mount-t vboxsf share/mnt/ubutushare
You must then log on as the root user, or you will not have permission to see anything. Enter the/mnt/ubutushare, you can see the files inside your Mac host, so that the host Mac download things can be shared, do not have to repeat the download.
Mac Virtualbox Ubuntu Settings shared directory