I was able to manage to make it work by doing some MySql googling.
I created the dbadmin user like so: CREATE USER ‘dbadmin’@‘localhost’ IDENTIFIED BY ‘123456’;
then I created a DB: CREATE DATABASE owncloud;
then I exited mysql
then I gave dbadmin access to the DB: mysql -h localhost -u dbadmin -p owncloud
then I input these credentials in the web Installation Wizard and created a user named ocadmin
And this time it worked.