As noted in the dev server (lobby) there were/are some issues.
Things should be fixed shortly.
Also your secret/jwt payload should be:
var payload = {
'exp': Math.floor(new Date().getTime() / 1000) + 60,
'user_id': channelID,
'channel_id': channelID,
'role': 'external'
}
Above is Signed JWT created by the EBS, following the requirements documented in Signing the JWT (in Building Extensions)
OR Twitch JWT containing the broadcaster role which is a JWT passed from a config/dashboard panel not a EBS constructed JWT