Thank you for the quick reply, but there are still errors:
After ./launcher start app
WARNING: We are about to start downloading the Discourse base image
This process may take anywhere between a few minutes to an hour, depending on your network speed
Please be patient
Unable to find image 'discourse/base:2.0.20190906-0522' locally
2.0.20190906-0522: Pulling from discourse/base
1ab2bdfe9778: Pulling fs layer
a313ca07f056: Pulling fs layer
1ab2bdfe9778: Download complete
1ab2bdfe9778: Pull complete
a313ca07f056: Verifying Checksum
a313ca07f056: Download complete
a313ca07f056: Pull complete
Digest: sha256:8c58bd323c80b464b2634d2aa8c322772d0c7bff3e08eff06cf2b66d37fe623d
Status: Downloaded newer image for discourse/base:2.0.20190906-0522
Unable to find image 'local_discourse/app:latest' locally
/usr/bin/docker: Error response from daemon: pull access denied for local_discourse/app, repository does not exist or may require 'docker login'.
See '/usr/bin/docker run --help'.