How to select a series of files from a geodatabase?

I am trying to mimic a step from a Training Course by Citilabs. The step listed below requires me to select Highway file from a geodatabase but I am unable to do so as the InputNetwork selector wouldn't go beyond the .mdb file. Any thoughts?

Step

How my network program setup looks like

Link to the Training Model files folder (the one I am working on)

Link to the Training Model files folder (the one I Citilabs supplied me with)