I did the following to setup MariaDB before using the installation wizard:
sudo mysql_secure_installation
# answer yes to all questions
sudo mysql -u root -p
create database nextcloud;
create user nxtcloudadmin@localhost identified by 'admin123';
grant all privileges on nextcloud.* to nxtcloudadmin@localhost identified by 'admin123';
flush privileges;
exit;
sudo nano /etc/mysql/my.cnf
# add these lines at the bottom:
log-bin = /var/log/mysql/mariadb-bin
log-bin-index = /var/log/mysql/mariadb-bin.index
binlog_format = mixed
sudo service mysql reload
Then try the wizard again where you use:
Username: skycorp
Password: skycorp_password
Database user: nxtcloudadmin
Database password: admin123
Database name: nextcloud
Database host: localhost
And don’t forget to change admin123 into a real password.
Good luck!