You can create a tree structure using a "Hierarchy" or "OrgChart" type of ShapeConnector.
The difference between Hierarchy and Org Chart is just how the third level of child shapes get attached to the parents.
When using the "Hierarchy" type, child shapes always go in a single row below the parent:
When using the default "OrgChart" arrangement, the third level of child shapes appear in a vertical column, rather than a row:
In both cases, the defaults can be overridden. So an "OrgChart" can be made to look like a "Hierarchy" chart and vice versa. It's simplest to choose the type where the default suits your needs.
Learn more about creating tree type diagrams:
Learn more about ShapeConnectors: