Since you are posting, you already have an Adobe account.
Have you tried accessing your account and registering the product there through your web browser?
To be honest, I don't see what possible benefit you could obtain from registering such an old, obsolete product that is no longer supported, but I could be wrong,
It's impossible. PS Starter has been braindead for 7 years now or so and is not compatible with contemporary versions of operating systems nor are the online services any longer available. You need to look for another product like PSE 11 or similar.