If you’re a new NerdWallet user
On the NerdWallet app or on www.nerdwallet.com, you can tap the “Continue with Apple” option on either the Sign-up or Log in pages.
When signing up with your Apple ID, you'll see an option to share your "real" Apple ID email or choose an "anonymized" email address generated by Apple, to provide to NerdWallet. All emails sent to the anonymized email will be forwarded to your real email address by Apple.
If you’re already a NerdWallet user
If you’re an existing NerdWallet user and you would like to sign in using Apple ID, you will want to ensure that your Apple ID email matches your existing NerdWallet account email.
If you choose to hide your email in the Apple ID flow (by using the anonymized email option instead), then a new account will be created instead of you getting access to your existing account. This new account will not show any of the information from your existing account, like your credit score or linked bank accounts. Nothing happens to your existing account in this situation; you can still access it by logging out of this new account and logging back in using your original sign-in method.
If you previously registered using "Continue with Google" only, you will be required to add a password to your account.
In other words, you must sign in using your existing sign-in method, like Google in the case above, and add a password to your account first before you can set up Apple ID sign-in.