Can't download VBoxGuestAdditions directly? Here's the solution!
1. Choose the right version of your software
https://download.virtualbox.org/virtualbox/
2. Mount the VBoxGuestAdditions.iso
Right-click Devices -> Optical Drivers -> Choose disk image -> find the VBoxGuestAdditions.iso
3. Install the VBoxGuestAdditions
Go to 'My Computer', go to 'VBox Guest Additions', install what you can install
4. Done
Reboot and enjoy it.
https://download.virtualbox.org/virtualbox/
2. Mount the VBoxGuestAdditions.iso
Right-click Devices -> Optical Drivers -> Choose disk image -> find the VBoxGuestAdditions.iso
3. Install the VBoxGuestAdditions
Go to 'My Computer', go to 'VBox Guest Additions', install what you can install
4. Done
Reboot and enjoy it.