He used a ductulator.
But, the ductulator, doesn't know what velocity, or FR is good for your system.
The person using it is suppose to know that.
He used a rule of thumb, and went with a .1"FR.
Unfortunately Thats .1" for every 100 equivalent foot. And unless he checked your whole duct system, and measured it up. He has no idea what your ducts equivalent foot is.
Next, he should know, or find out what the ASP(available static pressure) is that your unit has.
Your TEL (total equivalent length) could easily be over 300 foot.