Why do you need to verify my identity with my card number? And social security number?

How to apply for Apple Card - Apple Support states:

"If you're asked for more information

In some cases, Goldman Sachs2 needs additional information to evaluate your application. You could be asked to provide your full Social Security number. To protect your identity, you might also be asked to capture your driver's license or State-issued photo ID:

• Scan the front of your Photo ID and tap Continue
• Scan the back of your Photo ID and tap Continue

To rescan your Photo ID, tap Scan Again.3

Goldman Sachs might ask you to provide additional information on financial assets. In some cases, Goldman Sachs might request additional information about your relationship with Apple to further evaluate your application.

You can choose not to provide additional information at any point. If you choose not to share additional information, Goldman Sachs is unable to approve your application."

If this is in response to an email you have received, see below.

• Apple does not send such messages. 
• Apple would not warn of a pending account issue, giving you a deadline to fix the issue. 
• Apple does not include document, or PDF files to download.
• Apple would not refer to you as Dear Customer, Dear Client, or anything other than the name on file for your account.
• Apple would not have such horrible spelling or grammar. 
• Apple would not send a message to “Undisclosed Recipients”. 

It is a phishing attempt. Do not respond. Do not divulge any personal or financial information. You can use the address below to forward the suspect email message, as an attachment to Apple.

reportphishing@apple.com

The links below has information to help identify fraudulent emails.

Identifying legitimate emails from the iTunes Store

https://support.apple.com/en-us/HT204759