If you want to have your Meeting channels structured in your channel tree, you need to create Meetings channel.
You can set Meetings channel from channels settings:
Create a channel;
Go to the channel context menu by clicking on 3 dots button next to the channel name;
Click on channel settings from the channel context menu;
In the channel setting window click on Meetings Settings;
Click on Install and Activate.
When a Meetings channel is activated you can create Meeting channels under it to discuss a meeting details (topic, participants, time, etc.).
How to create a Meeting channel:
Click on Create new Meeting link under Meetings channel
or click on New Meeting from Meetings context menu;
2. Fill in the fields in Creating Meeting Channel window and click on Create.
A Meeting channel is created!
You can create Agenda Item channels under Meeting channels.