That has scam written all over it. Even if it does what it says, the certificate is only valuable if agents and editors know what it is and I'll bet you few people have heard of it.
I know quite a few ghost writers and none of them get gigs from being certified, they get them by being able to write well. They find work through their literary agents.
The other alternative is a book packager - packagers give the writer the outline and the characters and the writer does the words. The name on the front may be a pen name - but not always. Things like the Sweet Valley High or Babysitter's Club books are examples of book packagers works. Yes, I know I'm showing my age.
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are a book packager who are open to subs - I know of people who have been accepted, but I don't know of anybody who has worked for them. This kind of thing is often controlled by very tight NDAs so it can be difficult to find specific information about how it works.
DancingLady - a ghost writer can be used for anything. Celebrity biography is usually ghost written, as is celebrity fronted fiction.