Answered question

The error message indicates that an encryption algorithm required by the server is not supported by the JDBC driver version used by NeoLoad. If you get that error it probably means that you use an old NeoLoad version or the JDBC driver included in NeoLoad is too old.
Starting from NeoLoad 7.9.0 the JDBC driver version for postgresql is: postgresql-42.2.18.jar
If needed you can download a newer JDBC driver version from here

Replace the current JAR stored in $install_dir/lib/jdbcDrivers by the new JAR file and restart NeoLoad or your remote monitoring agent.

For more details about posgresql monitor please look at the NeoLoad documentation here