No sound whatsoever on iPad Pro (2018), refund rejected! How can I get a refund?

I just purchased Stardew Valley on the Apple App Store for my iPad Pro 11” (2018), however after downloading and installing the game, it played no music or sound whatsoever. Pure silence. Other apps play sound perfectly fine, and even after redownloading/installing the game, rebooting my iPad, checking sound options etc., there remains no sound.

When I tried to request a refund, I just got the message: We've determined that your purchase does not meet the conditions for a refund.

How can I get a refund for this game, since it clearly doesn’t work as it should?

Thank you.