Error video call

Installed and configured mattermost team edition ver. 3.6.2 (OS Ubuntu 16.04 LTS), the database on POSTGRESQL.
Downloaded docker https://hub.docker.com/r/mattermost/webrtc/. Do I need to initially install the janus server?
Pointed the settings in the docker, the admin console.
When you try to call says "Problem connecting to a video call".
What's the problem?
If you click on the link https://ip:7089/admin {"Janus":"error","error":{"code":454,"cause":"the request payload is missing."}}