How did this Zeus Hijack virus fishing scam appear on my computer? And what could the have done if I allowed them access to my computer?

Hi Kenneth,

You can find more information on this attack here:  https://malwaretips.com/blogs/remove-rdn-yahlover-worm055bccac9fec/

It wouldn’t actually do any harm to the computer and only lead to consequences if a victim cooperates with the scheme, calls the number, and provides his CC details etc.