Do not change the container port value, only the local port side (this goes for any docker container)!
Missing one more variable from the image:
YOURLS_SITEthat needs to match the domain name used when accessing this application.
Keep in mind that for this to work you will need a running MariaDB or MySQL instance where you have already set up a Database under the name of yourls and created a user and password that has permission for that database.
http://yourdomain.something:port/admin(also works via reverse proxy with https if you configure it, but then change the
YOURLS_SITEparameter to match your URL