Check with the recipient whether the indicated email address/phone number is associated with the recipient's account. If not, the recipient will not receive the money to their account until they associate their email address/phone number with the account.
To do that, the recipient needs to log in to their account:
Via website: select Settings > Payment Account and add the email address/phone number to the account.
Via mobile app: click on the top left corner for Settings (cogwheel) > View my profile > Link additional email or Link additional phone number.