Your screenshot says that docker can't register postgres database server because port is already blocked by a running process. Looks like you need to make sure to shutdown all running postgres services before. Is maybe an old version of greenlight already/still running? If you reboot your server standard greenlight docker-compose file makes sure greenlight is starting up again automatically. Try "docker-compose down" multiple times to shut down all processes, check if port 5432 is free and try "docker-compose up" again.
In addition to that executing your step 8 probably has reset your database password in greenlight config. If there was a working postgres database container before you now might have issues connecting to it because you changed the password. If you wanna start over from scratch, make sure, all existing docker images (including postgres images) are stop and properly removed before: Use "docker container list" and "docker images" to check.
Hope that helps.