StarPets Purchase Error - Cannot Buy Private Server Plus Despite Enough Funds

There is an error on StarPets that won’t let me buy anything. It keeps saying “Something went wrong! Try refreshing the page and try again.” I refreshed it several times, but it still didn’t work. I’m trying to buy the Private Server+ in The Strongest Battleground, which costs $3.89, and I have $3.90, so I should be able to purchase it. Please help me fix this issue.