Smoothly. You should basically be able to connect it with any existing bank account of yours. You don't necessarily need to have a credit/debit card in order to make PayPal work for you. Although I think no matter what bank account you have, the bank will probably have provided you with at least some kind of a card. This doesn't need to be a credit card, but it usually works with PayPal. You set up a PayPal account (= an email address), associate it with your card or with your bank account, and then you only submit your email address here on WGT, and you can buy credits via PayPal.
I have a credit card that absolutely doesn't work anywhere online, with one exception: PayPal. I tried buying credits with that card here, but the card got rejected. But when I entered the number of that card into my PayPal account, PayPal accepted the card, and I was then able to buy the credits here on WGT from that card. The card didn't work directly here on WGT, but it did via PayPal.