Digital Car keys

You need to enter your device passcode which you set up when you activated your iPhone. You may now use Face ID and may not have had to enter that passcode in a long time.

If you forgot your iPhone passcode - Apple Support

This article may shed some light on your issue. There is a limit to number and type of passes, ID’s and keys that can be used with >Express Mode.<

>>Select Express Mode for a transit or payment card, pass, or key

When you add an eligible transit card or other compatible card, pass, or key to Apple Wallet, Express Mode is turned on by default. You can also change which card, pass, or key is set to Express Mode.

• Multiple cards, passes, and keys with Express Mode can be active in the Wallet app at the same time. For example, you can have one student ID and one car key each set to Express Mode.
• With some cards, passes, and keys, you can't have multiple of the same type or from the same issuer set to Express Mode. For example, you can only have one student ID from the same school set to Express Mode.
• With some passes, you might be able to set multiple passes of that type to Express Mode.
• For transit, you can set one transit card to Express Mode for each transit network. You can also set a payment card that can be used to pay your fare in locations where your Express Transit card isn't accepted.<<

Use Express Mode with transit cards, passes, and keys in Apple Wallet - Apple Support