Why can't I use my SD card effectively?

[csoup223]

I have an unlocked Verizon branded Moto E4 with 16 GB of internal storage running Android 7.1.1. I have a Samsung U3 rated 128 GB installed and formatted to run as internal storage. For some reason, my phone still seemed to be ignoring this large amount of available storage. It is showing up but doesn't seem to be used. I read that not all apps are developed to allow them to be run on an SD card, even an SD card formatted as internal storage, but that some apps could and just need to be moved to the SD card. So I sorted through my apps one by one and changed the storage location. Oddly enough, many of my apps are now on "External storage" which is the SD card formatted as "internal storage." Great, this freed up a little room, however, my largest storage hog app, Pocketcasts couldn't be moved. After a little research I figured out I could designate a folder for Pocketcasts to store the podcast files in, but it doesn't give me an easy UI to create or identify a folder on the SD card to use. Instead, it just wants me to type out the file path. I have no idea how to write a file path for Android, but I figure how hard can it be? I'll just use a file manager app, create a new folder on the SD card and figure out how to write the file path to that folder. Except I've tried a few different file manager apps, and none of them seem to see the SD card at all. What am I doing wrong? It is incredibly frustrating to have the phone fill up the built-in-storage, only to have 116 GB of free storage begging to be used.