Extension pack and VirtualBox versions must match. The former can be found via File > Preferences > Extensions and the latter via Help > About.
USB Controller must be enabled in the VM configuration options.
VBox Guest Additions must be installed on the guest VM. With the VM running, click Devices > Insert Guest Additions CD Image and run the VBoxWindowsAdditions executable.
The user running VirtualBox must be in the vboxusers group. At the command line, run groups to see what groups you are a member of. If vboxusers isn't in the list, run sudo gpasswd -a $USER vboxusers to add yourself then REBOOT.
At least one filter must be set up under Devices > USB > USB Settings. Clicking the top icon on the right (USB plug with solid blue dot) will create a 'universal' filter for any device. When the VM is running, you should now see a list when you go to Devices > USB that allows you to select devices to connect.