According to this article we must chose between the Calendar API or the Cloud Communications API to create meetings. https://docs.microsoft.com/en-us/graph/choose-online-meeting-api We would lik...
I think this issue is quite similar: https://techcommunity.microsoft.com/t5/microsoft-365-developer-platform/post-api-to-create-calender-events-for-teams-channel/idc-p/3660123
It's about creating a calendar event for a channel, which might currently only possible for meetings (but I'm not sure).