Since MC is complied on Debian and the libraries are used are the same on Ubuntu which is derived from Debian, you can add the repo manually without any additional software.
For MC31 this applies to Debian Bullseye (11) and Bookworm (12) and for Ubuntu Focal (20) and Jammy (22).
For Debian only, the user may not be added to sudoers on a basic install.
If you get an error with sudo in the commands below, you can do the following in a terminal as the login user so the sudo commands work:
su -
(you will enter the root password that you used when creating the system)
usermod -a -G sudoers youruserloginname
(replace youruserloginname with the user name you logged in with)
exit
(to get out of the su -)
Then logout and log back in so that the change to sudoers works.
In a terminal as the login user, install any necessary dependencies:
sudo apt update && sudo apt install -y wget apt-transport-https -y gpg -y
Get and install the MediaCenter repo gpg key into a secure keyring:
wget -O- http://dist.jriver.com/mediacenter@jriver.com.gpg.key | gpg --dearmor | sudo tee /usr/share/keyrings/jriver-com-archive-keyring.gpg >/dev/null 2>&1
Create a repo list file
For Focal:
echo "deb [signed-by=/usr/share/keyrings/jriver-com-archive-keyring.gpg arch=amd64,i386,armhf,arm64] http://dist.jriver.com/latest/mediacenter/ focal main" | sudo tee /etc/apt/sources.list.d/jriver.list
For Jammy:
echo "deb [signed-by=/usr/share/keyrings/jriver-com-archive-keyring.gpg arch=amd64,i386,armhf,arm64] http://dist.jriver.com/latest/mediacenter/ jammy main" | sudo tee /etc/apt/sources.list.d/jriver.list
For Bullseye:
echo "deb [signed-by=/usr/share/keyrings/jriver-com-archive-keyring.gpg arch=amd64,i386,armhf,arm64] http://dist.jriver.com/latest/mediacenter/ bullseye main" | sudo tee /etc/apt/sources.list.d/jriver.list
For Bookworm:
echo "deb [signed-by=/usr/share/keyrings/jriver-com-archive-keyring.gpg arch=amd64,i386,armhf,arm64] http://dist.jriver.com/latest/mediacenter/ bookworm main" | sudo tee /etc/apt/sources.list.d/jriver.list
Note that you will be getting the same build of MediaCenter in all cases. The only difference is the repo name for your convenience.
To get the stable branch instead you can just replace "latest" in the code above with "stable"
Then to install MediaCenter simply:
sudo apt update
sudo apt install mediacenter31