On the bottom right corner of Bizagi Modeler are view options that help you to navigate through your process as is shown in the image below.
This menu can be also found on the View tab of the Ribbon.
Zooms the model to normal size (100%).
Zooms the page so the entire diagram fits in the window.
Zooms the page so the selected elements fit the window
Shows the pan window which can be used to navigate through the diagram.