Welcome to the community!
Please correct me if I am wrong, from my understanding, you wish to create a 'My TPG account' if that so, you can ask the original Account holder for the MY TPG Account log-in details and update it online.
Let me know should you require further assistance.
I just got approved to change the ownership of a tpg service, but I don’t have a actual tpg account. So i just want to know how i would go about creating one with out applying for a service.