I owe Apple Pay money back so I put the amount of money I owed back on my card but it’s saying my card is failing even though I have my card unlocked

I wanted to pay apple back for the money so I bought a Apple Pay card w the amount that so I added my cash app card to

help it go through because I can’t download apps without paying them back so I try to add my cash app card but it says failed every time but my card is unlocked and I have 30$ on my Apple Pay account for Apple Store.