You have not yet received an e-mail that you can use to link your PayPal account with your Nintendo Account.
For any other types of e-mails, (Parental Control PIN, part orders, general correspondence), click here.
What to Do:
Click “Send E-mail” again in the Nintendo eShop (on-device or off-device) to resend the PayPal confirmation e-mail.
Check your spam / junk e-mail folder to see if the e-mail is there.
Make sure there are no filters in your e-mail account that may be blocking e-mails from @accounts.nintendo.com.
Check your Nintendo Account profile settings to verify the e-mail address.
PayPal verification e-mails are sent to the e-mail address associated with your Nintendo Account – this may be a different e-mail address than then one associated with your PayPal account.
Try changing your Nintendo Account e-mail address , then click “Send E-mail” again in the Nintendo eShop to send the PayPal confirmation to the new e-mail address.