Let's go through it once more.
https://coronavirus.jhu.edu/from-our...-misconception
They state that NYC has 15-21% infected. That gives that actual cases are 6-9 times actual cases, and combined with the number of deaths they give it indicates an IFR of 1-1.4% (or higher) - and they also state the IFR for a cruise ship to be 1%.
The chickenpox IFR comparison indicate that their IFR is above 0.29%, and since it's such a rough estimate it's likely that they mean it's higher.
They then state that to reach 200 million cases with 25k confirmed cases a day it will take well into 2021, i.e. about 300-600 days.
If actual cases are the same as confirmed cases it would be 8,000 days.
If actual cases are 6-9 times confirmed cases - as for NYC then it is 880 days or more, which is beyond 2021.
And if they have an IFR there is no need to count number of days to reach case-numbers to figure out the total number of deaths.
The text uses references 1-10, the reference list has 9 entries.
I don't see how anyone can claim that the numbers make mathematical sense.