Hey there, erik8thw!
It's highly unlikely for the phone to recognize the WD My Passport external drive, especially if it's formatted in NTFS. Android requires an
exFAT or FAT32 format on the drive in order to recognize it.
(Keep in mind that reformatting would erase all the data on the WD My Passport drive) Mechanical hard drives require a bit more power, which the phone is most definitely unable to provide. You should also know that the mechanical external HDDs are not designed for phone use anyhow.
If you need a backup drive/destination for your phone data, you might want to consider using Dropbox.
Your Dropbox account can easily connect to WD SmartWare Pro and allow you to backup your phone data to...