A possible solution to not being able to download episodes.
Disclaimer: This may not help your problem, but this is what I discovered and my theory about the problem.
I encountered the problem where you would download episode 2 or any of the episodes and it would stop at a certain percent each time, and say my network was unavailable. For episode 2 it was 66% , I have tried redownloading, reinstalling and even did a full restore on my device, but to no avail.
So I walk into McDonalds the other day and bought something to eat and decided to give it one last try to downloading the episodes. To my surprise the episodes downloaded. For episodes 2-3 it started where it would glitch off in the download, episode 2 was 8%, episode 3 was 15%. Episode 5 I didn't download due to time constraints. But it was the very fact of why, that confused me. Why couldn't I do at home at my Wi-Fi but when I used McDonald's Wi-Fi it suddenly worked. The only possible answer I could get was that their server connection was not strong enough in some places and would result in the problem network unavailable, even through the Wi-Fi network you were using was completely fine. it seems McDonalds had a strong enough Wi-Fi network to reach telltale game's server, which makes sense , since McDonald's Wi-Fi is commercial and is meant for lots of people to use, so it had to be strong. This is just my theory , by no means is it correct or verified yet. So the solution here is to go to a nearby McDonald's or a place with strong WiFi and try downloading the episodes.