Https://guacamole.apache.org/doc/1.2.0/gug/jdbc-auth.html#jdbc-auth-postgresql
the main difference is bitnami is pre built with postgresql so when the instructions mention mysql and MariaDB you'll have to use these instructions. I'm still working though this but I'm creating bitnami instructions on the side. However if bitnami devs could make the instructions too I can assure you they will be better than mine haha