Hi! By creating a team you have already created a group behind the scenes!! But it won’t show in Outlook by default since it was created from Teams!
You can get to the calendar by going to the files tab -> click ... -> open in SharePoint -> Now you are in the groups Team site which is one of the workloads created with a group :) Click conversations in the left menu and it will take you to the group inbox, with the calendar included!
You might also set up the group calendar webpart on the itself to see events from the calendar! Then add it as a SharePoint tab in Teams! Just an
In order to make it visible in Outlook you need to Use PowerShell: