I was unable to add money to my apple id account

Did you read/try the links posted above?

Buy/redeem Apple Gift cards to the account.

Apple Card  -

Gift cards redeem.   *

ASC YouTube for how to redeem an Apple Gift Card | Apple Support

Gift Card - can’t redeem.   *

See the following Apple articles:

Change, add or remove Apple ID payment methods

Change, add or remove Apple ID payment methods – Apple Support (UK)

Add money to your Apple ID balance

Add money to your Apple ID balance – Apple Support (UK)

Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)