Can't update games on iPad without billing info

Hi cristy165,

Welcome to the Apple Community.

( We are all Apple users like yourself, doing what vows can to help troubleshoot.)

Re: "Why can’t any of my games update"

How apps, content and subscriptions from Apple are billed:

https://support.apple.com/en-au/HT201359

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Re: "I have a balance of $20 from a Apple Card"

Wondering if you added the Gift card to your Apple ID account,

or

'if your country or region is on the accepted list for that.

Apple ID balance isn’t available in all countries or regions. 

May be check if you can pay with your Apple ID:

Payment methods that you can use with your Apple ID:

https://support.apple.com/en-au/HT202631#methods

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Re: "What can I do?"

The App Store requires an acceptable payment method in your Apple ID account, for the first time you use the App Store.

How to Change, Add or Remove Apple ID Payment methods

https://support.apple.com/en-us/HT201266

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After you have used the App Store or iTunes for the first time, 

it is possible to remove the payment method.

How to remove payment methods from your Apple ID.

https://support.apple.com/en-us/HT204034

or

If you can't remove your last payment method or use no payment method with your Apple ID

https://support.apple.com/en-au/HT203905

All the best :-)