Office 365 Groups are the underpinning for how you collaborate with other team members across Office 365, from SharePoint to Microsoft Teams.
- A team in Microsoft Teams is always associated with an Office 365 Group
- An Office 365 Group is not necessarily Teams enabled
To enable Microsoft Teams for an Office 365 Group, follow the steps in this Microsoft Support article: Create a team from Existing Group
Once the group is Teams-enabled, it will become visible in Microsoft Teams Teams and you can create Team and Channel meetings with Decisions.