I followed the directions smoothly till the step:
For this example, find the Microarray and Gene Expression Data (MGED) ontology from the drop-down list, either by typing in the first few characters in the ‘Filter’ field box, or by scrolling down the list, select the entry, and then click ‘OK’.
I got the ontology classes and subclasses at the right pane. However, it didn't open within the Excel sheet; not by double clicking the ontology nor the class name.
Can we advise what may be wrong at this point...?