Why can't I buy credits on Rocket League?

I'm having an issue with purchasing credits on Rocket League, can you help me understand why I'm encountering this roadblock? I've tried multiple payment methods but to no avail. Is it a technical issue, a regional restriction, or perhaps something else entirely? I'd appreciate any insight you can provide to get me back in the game and spending my hard-earned money on those sweet, sweet in-game items.