Ubuntu 20.04 にMariaDB 10.6 を入れます。公式サイト参考に（簡単です）。

Deploy MariaDB Community Server 10.6 - Install via APT (Debian, Ubuntu)

wget https://downloads.mariadb.com/MariaDB/mariadb_repo_setup

echo "733cf126b03f73050e242102592658913d10829a5bf056ab77e7f864b3f8de1f mariadb_repo_setup" | sha256sum -c -

chmod +x mariadb_repo_setup
./mariadb_repo_setup --mariadb-server-version="mariadb-10.6"
apt update
apt install mariadb-server mariadb-client mariadb-backup
apt install mariadb-plugin-mroonga

初期設定スクリプトを実行。

mysql_secure_installation