You can download the Vertica drivers here:
https://my.vertica.com/download/vertica/client-drivers/
Once you have the files you want (i.e. vertica-jdbc-9.2.1-0.jar) you should be able to run a command something like the following to add it to your local repository:
mvn install:install-file -Dfile={/path_to/vertica-jdbc-9.2.1-0.jar} -DgroupId=com.vertica -DartifactId=vertica-jdbc -Dversion=9.2.1-0 -Dpackaging=jar
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