Outer Wilds DLC not showing up in game and refund request denied

I bought the Outer Wilds DLC "Echoes of the Eye" for 10$, only for it not to show up in game. Over a few days, I tried a bunch of different solutions and nothing worked so I contacted support to make a refund. My request was denied with the description "Refunds aren't available for digital purchases that have been played or used." How am I supposed to "play or use" a game so that it is able to be refunded if the game doesn't work in the first place? The DLC will not show up in Outer Wilds. I paid my own money for it that I had been saving up and support is telling me that even though the DLC is not working and I cannot play it, I also am not able to refund it because I haven't played it. How does this make sense?? I just want to refund the DLC. Does anyone know how I'm able to get a refund, or even how to solve the DLC issue? (I'm playing on pc, not the xbox console)

:)