I’ve managed to install Xibo doing this:
wget https://github.com/xibosignage/xibo-cms/releases/download/4.2.0/xibo-cms-4.2.0.zipxibo-cms-4.2.0.zip
unzip xibo-cms-4.2.0.zip
cd xibo-cms-4.2.0
cp config.env.template config.env
Edit the mysql_password variable to a very simple password using 16 characters.
Mine is similar to this example: word1111word1111word
Now, do sudo docker-compose up -d or docker-compose up -d
If everything goes wrong, remove it and try again with sudo docker-compose down -v or docker-compose down -v