Hi there,
This previous answer may help you:
’Please ensure you have verified your identity in the Apple Cash Card. You can do this in the Wallet App by tapping Apple Cash, then tap the 3dot menu. Tap Card Details, then tap Verify Identity near the bottom of the page. Then - You can initiate an Apple Cash transfer in the Wallet by tapping Apple Card. Tap on Savings, then tap Withdraw or Add Money. Enter the amount you wish to transfer, then tap Next. You will see Apple Cash as a transfer option.
The above is word for word from Apple Support. However, the last few steps were a little different for me when going into Apple Card after verifying my identity. After tapping on Savings I had a box asking me if I wanted to transfer my Apple Cash balance. I clicked on that and followed the prompts. ‘
Moreover, you can automatically transfer daily cash to your saving account if you have an Apple Card.
To learn how to do so and get more information about how to use Apple Savings, see: Set up and use Savings in Apple Wallet - Apple Support