EDIT
As a result of running ‘pwd’ your should run the Docker cp command as follows:
docker cp 143v73628670f:/opt/jboss/keycloak/themes ~/Development/Code/Git/keycloak-recognition-login-branding
You are forgetting the trailing “https://stackoverflow.com/”. Therefore your command should look like this:
docker cp 143v73628670f:/keycloak/themes/ ~/Development/Code/Git/keycloak-recognition-login-branding
Also, you could make use of Docker volumes, which allows you to pass a local directory into the container when you run the container