Update: Now Jellyfin has provided a BASH script for APT user: https://jellyfin.org/docs/general/installation/linux/#debuntu-debian-ubuntu-and-derivatives-using-apt

Overall it's quite straightforward, especially when compared with installing the LAMP environment or WordPress, thanks to the APT package manager.

For the Ubuntu server, refer: https://jellyfin.org/docs/general/installation/linux#ubuntu

sudo apt install apt-transport-https

sudo add-apt-repository universe

curl -fsSL https://repo.jellyfin.org/ubuntu/jellyfin_team.gpg.key | sudo gpg --dearmor -o /etc/apt/trusted.gpg.d/debian-jellyfin.gpg

echo "deb [arch=$( dpkg --print-architecture )] https://repo.jellyfin.org/ubuntu $( lsb_release -c -s ) main" | sudo tee /etc/apt/sources.list.d/jellyfin.list

sudo apt update

sudo apt install jellyfin

Done.