Thanks again for your answer.
Emby does not run by default on port 80. Port 8096 is the default but you can change it to the one you want. Docker is excellent, I was a little worried about the future support for Emby or Plex in OMV and the next version.
By the way .. TODAY: Debian Buster (Debian 10) will be officially launched https://bits.debian.org/2019/07/upcoming-buster.html and I assume that's something the OMV developers were waiting for new version.