When I tried to add Guest-Additions by clicking "Devices" and selecting the "Insert Guest Additions CD image" option, a pop-up that said:
showed up.Could not find the VirtualBox Guest Additions disk image file.Do you wish to download this disk image file from the Internet?
Clicking Download then brought up this pop-up that said:
And then nothing happened after that. The Guest Addition ISO wasn't mounted and I wasn't able to install the Guest Additions.Downloading Guest Additions...\n Name: VBoxGuestAdditions \nDuring certificate downloading: Unknown reason".
If someone can help me add the Guest Addition to my VM, I would be very grateful. Also, please note that I'm rather new to Linux.