In relation to this I added US Barclayscard to my AliPayHK. I'm having trouble with my US Capital one credit card, and I haven't been able to get my US Chase credit card to be added to AliPayHK despite calling Chase and AliPayHK. I'm hoping it'll work eventually because as far as I know AliPayHK is the only free way I know that I can use a US credit card to pay HK government rent, HK water bills, HK electric bills, and more bills just by scanning a QR code? Feel free to PM me if you know of other QR code scanning apps that let you use a US credit card for free to pay so many HK organizations that don't directly accept payment via credit cards.
Anyway, open an AliPayHK account, if someone refers you they'll get a tiny referral bonus. Try to add whatever credit card you want and see if you can complete your transaction with your merchant's QR code or some other method they can tell you about for paying them using AliPay.