Found the issue. I needed to turn off Mod Organizer's FOMOD installer plugin to allow for the internal FOMOD to activate. This installed the required files. Thanks for the help.
EDIT: For clarity to anyone else having the same issue, click your settings button in Mod Organizer. Click the Plugins tab. Select Fomod Installer from the list. Double click prefer and change the setting from true to false. Exit out of the settings tab, and reinstall Greatsword Sheaths and Scabbards Redux per the STEP Guide instructions. Once it is installed, go back into your settings and turn the preferred setting for the Fomod Installer back to true.
MonstarVirus's post in Missing Texture for Ebony Blade Sheath was marked as the answer