Connecting to a shared database

I have 2 VMs (devbox, devbox-2) which are seemingly talking to eachother (seemingly confirmed by the logs of devbox, but not devbox-2), however I am trying to connect them to a shared database on a 3rd VM (devbox-database), and am having some issues setting the database up. I have installed and setup postgresql following this guide: How To Install and Use PostgreSQL on CentOS 7 | DigitalOcean

Is there some other database setup I need to do before I can get the two keycloak instances to use the same one to sync their data?

devbox log: