Thanks for stopping by the HP Support Forums! I will do my best to assist you with this issue 🙂
I understand that you are trying to register your printer. You can log in to https://register.hp.com/ to complete the product registration.
Could you provide me with the exact model of the printer and the Operating system installed on the PC? Use this link to find it: https://support.hp.com/in-en/document/c03754824 (Ensure you do not share any of your personal information such as serial, phone number, email ID, etc...).
Please respond to this post with the details of the product so that I can provide you with an accurate steps which should help you resolve this issue.