Hi Kareemelhosseni,
welcome to the Apple Community.
Re: "My wallet doesn’t add credit cards".
You might want to check that you are signed in (to your device) with your Apple ID:
Sign in with your Apple ID - Apple Support
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Re: When I press on “ ” it says to add card from app, and when I try to add it from app it says error.
Seems this is the screen where "add card" means store cards and the like,
(ie :is not the screen for add credit / debit cards.)
How to check if Apple Pay is available in your country or region: and, if so, the Apple Pay participating banks
Countries and regions that support Apple Pay – Apple Support
and
How to check if your device is compatible:
Devices compatible with Apple Pay – Apple Support
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Trouble-shooting:
What to do: If you can't add a card to Apple Wallet to use with Apple Pay - Apple Support
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Hope this helps:
NB: We are all Apple users, like yourself, in this community.
(ie: We have no access to your accounts or details.)
For more support, if needed:
Try reaching out to Apple Pay Support Staff
(eg: scroll to the link at bottom right on their website that opens from the link below.)
Apple Pay - Official Apple Support
All the best :-)