this is good one.
some problems i faced to apply this theme because two-step module is not installed as predefined on ubuntu .
i dont understand why.
I convert the rpm to deb format two-step-plugin *transfer from files tab*
In mint xfce i was able to apply
install two-step-plugin
copy two-step from usr lib plymouth to usr lib i386gnu plymouth
then install plymouth-themes
and apply with your native command
in my case it works with the following
sudo ln -sf /usr/share/plymouth/themes/greatest/greatest.plymouth /etc/alternatives/default.plymouth

sudo update-initramfs -u

and reboot