Purchase membership pack upgrade via paypal using UnionPay card

Hello Reiza studio, I have the Automobilsta on steam by purchase the GSC before. Now I try to upgrade it to Menbership Packs, but it seems that your seller account does not support UnionPay card payment on Paypal.
I have bought some other games on paypal before by using Unionpay card without problem, it seems it's up to the seller's setting. Could you please check if it's possible to make it easier for me to buy the great pack? Thanks