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.