Hello joan_darc,
For assistance with having your card information automatically fill, check out the steps below to see if this is enabled. Keep in mind that some websites may not allow information to automatically fill, so this could be related to what you're noticing. For more information, you can also check out this resource: Automatically fill in your information on Safari on iPhone
Set up AutoFill
You can save your personal information or credit card number on your iPhone to speed up filling in online forms and making purchases.
1. Go to Settings > Safari > AutoFill.
2. Do any of the following:
• Set up contact info: Turn on Use Contact Info, tap My Info, then choose your contact card. The contact information from that card is entered when you tap AutoFill on webpages in Safari.
• Set up credit card info: Turn on Credit Cards, tap Saved Credit Cards, then tap Add Credit Card. Enter your credit card information into the fields provided or tap Use Camera to enter the information without typing.
You can also save the credit card information when you make an online purchase. See Make your passwords available on all your devices with iPhone and iCloud Keychain.
If that information isn't helpful, provide more details so we have a better understanding.
Have a great day!