Allen had already known that there was a Supreme in his world who owned the
"System, activate the Trade Feature reward and integrate it in the Alternate Multiverse Chat Group so that my chat group members can use it."
But first, Allen ordered the system to publicize his Trade Feature so that all of his chat group members could use it.
[Ding!]
[The Trade Feature has been integrated into the Alternate Multiverse Chat Group!]
It wasn't a system message only exclusive to him since it was an announcement made by the AMCG System in the AMCG Platform. So all of Allen's chat group members have read the announcement made by the system.