Why Weverse shop payment isn't available?

I'm just going to buy The Sin Vanish Album on Weverse, perfectly completed all required information of mine, and when it comes to check out page, I clicked Accept and Pay by PayPal and trying to fill out my email for logging in, but it kept returning to the page says "something went wrong, returning to merchant" like what???????

I'm so confused rn whether it's just technical issue due to too much active users or what? btw I'm a foreigner from Thailand, is there something relatable causing that issue??????