Hello @Dukemaster,
The easiest to add MariaDB repository is to use the repo_setup_script provided by MariaDB :
# replace 10.x with the release you want to install (eg . 10.1, 10.2, 10.3)
bash <(wget -qO - https://downloads.mariadb.com/MariaDB/mariadb_repo_setup) \
--mariadb-server-version=10.x...