Default [Q] Need help with EZpdf "Open in New Tab"

Recently I found out EZpdf Reader app has a feature "Open in New Tab". I love it.
However, when I tried to show my dad how to use it, the feature didn't work right in his tablet.
Normally when you tap the feature, options come up for file management/browser apps available on the device its running on. My dad and I both have ES File Explorer. Selecting the feature in EZpdf Reader on my tablet, the option shows up. Selecting the feature in EZpdf Reader on my dads tablet, it automatically opens "Downloads" to search for a desired PDF file. I tried to clear defualts, but EZpdf just doesnt seem to want to provide any other options for apps on my dads tablet. Can anyone help explain why this might be

Im on Samsung Galaxy Note 8.0 Jellybean
He's on Samsung Galaxy Note 10.1 KitKat.