Go and follow this instructions carefully otherwise it won't work. Open your terminal.
First update your system 'apt update' and upgrade it 'apt upgrade' and to satisfy the dependencies run:
$ sudo apt install plymouth
Upgrade yourself to root if you are an expert outherwise use sudo before every command! we are assuming you are not upgrading yourself to root.
Now install wget
in case you don't have it.
$ sudo apt install wget
Now let's download our theme package.
$ wget -P ~/Downloads https://github.com/EdiTechStudio/Plymouth-Theme-v2.0/raw/main/glug-splash-screen-plymouth_2.0_all.deb
Now run the command
$ sudo dpkg -i ~/Downloads/glug-splash-screen-plymouth_2.0_all.deb
And you are done!