To add a Team to an Office 365 Group we have two options:
From Tams we can create a new Team from an existing Group.
From the home page in a modern SharePoint Online (SPO) site, we can also create a new Team.
In this article we will review the second approach. Basically, as soon as we create a new modern SPO site in our tenant, we will see a Microsoft Teams banner in the site home Page. This banner contains a short explanation about what you get when you use a Team for communication and collaboration and also a “Create a Team” link.
When you click on “Crate a Team”, the browser automatically tries to open Teams Client (Web or Desktop one) showing the new Team created:
Additionally, in the site navigation a “Team” link has been added providing a shortcut to the Team crated.