You don't need to rely on Virtualbox addition.

You have first to create a shared directory lets say we want to make it on Ubuntu.

right click on the folder you want to share then go to sharing options , you'll see this

Now click on the check box beside Share this folder and specify permissions down.

On your windows machine now run the run dialogue super+r Then enter the Ubuntu-ip

Now you can show the shared folder and thus you can share your files and folders easily

For more information check this