The Form's source is here .

How to import Form into the system see here . 

Create and save a new form

Launch an XLSX Workbench, and create a new form with name ORGUNIT_HIERARCHY_1 .

Assign a context to the form

Assign a context CL_HRPAYNA_GUI_ALV_TREE to the form. 

When an automatically creation of the Form structure will be prompted, you should press the button

to create a structure manually.

 Go to Excel menu: Data > Outline and uncheck the checkboxes in the popup-window (if they are set):

Create a Form structure

Add the component «Tree» under the component «Sheet»:

Template binding

Assign component «Tree» to the marked-up area of Excel-template :

Context binding

Assign component «Tree» to the context root node :

Activate the Form by pressing a button 

Explanations

This example explains that, it is enough a single component «Tree» to insert an CL_GUI_ALV_TREE into the Printing form.  

You only need to assign «Tree» to the the template area and assign «Tree» to the CL_HRPAYNA_GUI_ALV_TREE (CL_GUI_ALV_TREE) of context.

There are many formatting options available in the Properties tab for the «Tree» component :

ALV Tree Excel SAP ABAP