Your resultant path is wrong:
"C:\Users\arily\Documents\GitKraken\DND-Astra\Astra\UnityEngine.Networking.UnityWebRequest"
Surely that should be something more like,
"C:\Users\arily\Documents\GitKraken\DND-Astra\Astra\myfile.json"
I think you've got this part wrong:
FileBrowser.Result[0]
Should probably be something like FileBrowser.Result[0].fileName as its currently converting an object to a string representation.