Production with Oracle
If you operate Oracle DB on different server than midPoint without SSL tunnel or dedicated network, you should think of securing your JDBC connection will SSL/TLS. Oracle manual may help you with that.
Download Oracle JDBC Driver as JAR for JDK 10+ (or for JDK 8, if you insist) from Maven repository or directly from Oracle pages e.g. for Oracle 19c here. Drivers are generally broadly compatible, but newer is probably better.
Developer setup with Vagrant for Oracle XE 18c
Complete prepared Vagrant box (except for files that need to be downloaded) is available here: https://github.com/virgo47/midpoint-vagrantboxes/tree/master/vagrant-midpoint-db-oracle-xe
Download the directory, make it current (Vagrantfile must be in the current directory) and see the provided README for instructions.
When required files are prepared inside tmp directory, one vagrant up (and waiting) should get you to the point when you can run midPoint against the database.
Configuration sample above can be used, only jdbcUrl must be changed. Enjoy.