What was their reason for declining?

They are, actually. They’re a registered non-profit.

I see they’re a non profit business. That doesn’t make them a charity. They have paying customers.

https://github.com/TryGhost/Ghost

This is the repo (unless I have the wrong software).

However, it seems they’re running a business, which means revenue generating features will probably be prioritized. They’re not running a charity.

I’m sure if you donate enough money you can probably get them to implement better self hosting functionality. Chances are the email requirement is just what they have for other features.

It doesn’t seem like Steam is the right venue for a student project. It’s not a place to receive basic feedback which students or novices would need to improve.

$100 is nothing compared to how long a game costs to make. Hundreds of development hours is tens of thousands of dollars. And if you’re making a game for less than a hundred development hours… maybe it’s not a very good game?