When opening a Base Enterprise account, the Account Owner is placed at the top of the hierarchy tree making them the "topmost manager". To begin building out your team structure, you can add users above or below the toplevel Manager (Account Owner) using the + (Add User) button.
Continue to build out your hierarchy tree by adding each new user on the same level or below the last. Once you've created a user with subordinates beneath them on the hierarchy tree, you've successfully created a Team.
What is a Team in Base?
A Team is a group of all subordinates under one user. You can customize your Team's name to make it unique and easily identifiable. Setting a Team name is especially handy when viewing your sales reports.
What is a Group in Base?
Groups are a defined subset of a Team. Using Groups is a great way to segment and filter your reports. Groups propagate downwards. When assigning a user to a Group, that user's subordinates will also be included in the Group.