You're saying that you found an affiliate site with 700 authority backlinks.
You didn't break down those authority links.
Are they all unique links from 700 different domains?
Chances are, they probably are repetitive links from quite a narrow range of domains.
If that's the case, then this should be fairly easy to replicate if you know how to reverse engineer the backlink footprints of your competitors.
Also, I highly doubt that all these links appeared in the span of two weeks.
It's highly unnatural and chances are, the target website would probably get banned.
Just as anything that can be done with backlinks, you can easily reverse engineer your competitors.
You can look for lost links or broken links and try to get links that way.
You could also try to get links from their same link sources by offering superior content.
There are so many ways you can play this, but 700 authority links, assuming they come from fairly a narrow range of domains, is definitely doable.