Make sure that the Cloudera Director server is still running by using `ps` on its machine. Also check its application.log file to make sure there were no problems with it starting up. You should not have to set JAVA_HOME for Cloudera Director, because the startup scripts that ship with it hunt for a JDK or JRE to use. (This is not a cloud-specific thing.)
Assuming that Director is running, try to access it locally from the machine it is running on, e.g., `curl http://localhost:7189`. If that works, then the server is running normally; otherwise, check the logs.
Once Director is running normally, see if you can reach it from your browser. If you are running on a machine that is not inside the same GCP network where Director is running, and you do not have a VPN connection established to GCP, then you must access Director through the public IP address associated with Director's machine. In that case, firewall rules must allow inbound TCP traffic over port 7189 from your IP address / range.