Can you try to remove the container, then remove the openrct2 folder that's located in your appdata directory and then try to pull a fresh copy from the CA App.
After that let it fully start, stop it, edit your config, start the container and try to connect.
This will make no difference in terms of the password.
Yes because you don't did the necessary port forwarding, it will only show up when the master server is actually able to connect back to your server and that's only possible if you did the port forwarding properly.
!!!! Please leave this value at null otherwise it won't work properly !!!!
As said above I tried this on my server with a fresh pulled copy from the CA App, let it start, stopped it, changed the config (only edited the server name), did the port forwarding and started the container again.