I'm not certain that a computer fan is rated at enough air flow to force air through that scrubber.
Just for comparison, you need an actual BLOWER to run an odorsok properly, which is about the lowest-air-resistance carbon filter I can think of.
I think that guy may be ripping people off with a product that does not perform up to what is expected of it.

More ducting will quiet it down, but you may have more significant problems.