In Step 9b in the section about setting Oracle DB as a repository:
The /path/to/openidm/db/oracle/scripts directory includes an ojdbc8.bnd file that specifies the version information for your JDBC driver.
There is no file ojdbc8.bnd present in the above directory. The only .bnd file present in the IDM distribution is <openidm>/db/mssql/scripts/sqljdbc4.bnd
Workaround - manually create the ojdbc8.bnd file using the example listed in step 9b.