Verizon is aware of this issue. Customers do not need to be concerned as they will automatically receive the card after 65 days. There is no need to register, as long as your order was completed through August 31, 2018.
Any orders completed after September 1, 2018 require registration according to the promotion.
Here are examples of the confirmation email which is sent to the customer once an order is submitted:
A $xxx credit towards a range of smart home devices. You'll receive an email with instructions to redeem your $xxx credit approximately 30 days after your Fios service(s) are installed.
A $xxx Verizon Visa Prepaid Card. You will need to register for your card in order to receive it so expect an email with registration instructions approximately 30 days after your Fios service(s) are installed.