virtualbox – Missing CDRom on Ubuntu Server install inside a Virtual Box VM on Windows 10 Pro host

I have just downloaded Ubuntu Server from Ubuntu website.

I have installed Ubuntu Server inside a Virtual Box VM on a Windows 10 Pro Host (This host does NOT have a physical CDRom drive)

I have gone to install the Virtual Box Guest Additions but there is no virtual CDRom.

I tried various different tutorials with sudo around…

mkdir /media/cdrom
mount /dev/sr0 /media/cdrom
cd /media/cdrom
sh VBoxLinuxAdditions.run

however the CDRom was either not created or was created inside the media folder but I could not access it as it kept saying I did not have permission.

Can someone tell me how to create a virtual CDRom so I can install the Virtual Box Guest Additions.

I have wiped the previous tries of VM, so now I just have a vanilla install of Server ready to start again.
Thanks