Anyone know how I can get a refund so I can buy the deluxe edition? Does it take a while to process and I'm better off just buying the deluxe now while its on sale?

You should contact support.
If you haven't tried to download the version you accidentally bought, you can use the 30-days money back guarantee.
It's Saturday so it could take a while.

You can buy the Deluxe Edition now as a gift and redeem it after the refund is complete.But only if you haven't tried to download any files, else the refund is not guaranteed.

Alternatively you can buy the Deluxe Edition Upgrade. Total cost will be a bit higher though.

It's just a single scenario and by no means better than any random map.