I don’t understand the PayPay credit card

PREFACE: I don't need the credit card for anything serious, I have cash and savings. This is just annoying. I'm still thankful for answers, though.

I recently (last November) got PayPay and applied for a credit card as well and got it pretty quickly. It seems I only have a balance of 200k Yen on it.

My bank account is connected to PayPay.

I've spend the money, now there's nothing on it anymore.

I've waited for the end of February, for the balance to be restocked from my bank account, because for the life of me, I could not find any way to top it up manually, like you can with your PayPay balance. (Inline Edit: I should've clarified, that there was a payment supposed to go off on the 27nd of February, which did not happen, which is most of the cause for my confusion).

February came and went and my credit line was not topped off, but there is a charge already earmarked for the end of March for some reason.

Apparently you can't just trigger this now, you can only delay it further. It seems like I can't send my PayPay Balance onto the credit card.

Am I that blind, or is this just a supremely useless piece of plastic?

EDIT: I struck through "recently". I got the card last fall.

EDIT 2: A payment of 122k went from my bank to PayPay on the 27th, but apparently it might still take a few days for that to show up, as some commenters mentioned.