I agree, but you haven’t told us which bit you’re stuck on.
So, here:
sudo pacman -U https://archive.archlinux.org/packages/v/virtualbox/virtualbox-6.1.12-3-x86_64.pkg.tar.zst https://archive.archlinux.org/packages/v/virtualbox-host-dkms/virtualbox-host-dkms-6.1.12-3-x86_64.pkg.tar.zst