SonarQube will listen by default on port 9000, as set on your $SONARQUBE_HOME/conf/sonar.properties file, in the sonar.web.port parameter.
Beyond this, if you do not manage to access it from outside your AWS VPN, you will need to check your networking setup on the AWS side. We cannot really help with this. Still, and without being an expert, I would recommend to check your EC2 instance’s Security Group and/or ACL settings to make sure port 9000 is open for the outside world.