Continuing with the installation of VirtualBox, we now would need to add VirtualBox Oracle VM VirtualBox Extension Pack into VirtualBox.
First, open the application by location the VirtualBox icon on your Applications folder and double click on it
This will open the VirtualBox application which will show up the Welcome screen.
On the VirtualBox menu select the Preferences menu item.
By default, the Preferences windows shows the General options.
Select the Extensions option.
Then click on the Add icon located on the right side of the window.
Navigate to the Downloads folder and select the file with the vbox-extpack extension that was downloaded
from the VirtualBox website.
Then click on the Open button.
A dialog window will indicate that we are about to install a VirtualBox extension pack.
Click on the Install button.
A window with the VirtualBox License will be displayed where you can read the License.
When you reach the bottom of the license, the I Agree button will be enabled. Click on it to continue.
A popup window will show the progress.
Then, you would be required to enter the password of the admin's user of your machine.
Another popup window will show up indicating that the installation was successful.
Finally, you will see that the Oracle VM VirtualBox Extension Pack has been added to the list of extensions.