PIN access with Android app

I want to know if it is possible to enable some sort of PIN or password access to a folder I am accessing via my Android phone. When I log into my WD Android app I can pretty much access all my files and folders on my WD Mybooklive NAS. However what I want to happen is that I can lock down particular folder so if I click on them some sort of authentication pops up. Is this possible on this device? I have the WD Mybooklive 2TB.