>doesn’t seem to get anything unless the exit is > $35M.It's because their model assumes "$41 million" was invested into the hypothetical seed company over 4 rounds. Therefore, the company has to exit for more than $41m for the employees' common stock to be worth something.
You have to click on the "How We Guesstimate" button to see their underlying financial assumptions.
In my opinion, this type of "what if?" calculator would be easier to understand if they explicitly showed the intermediate calculation steps in the user interface. A more obvious "show your work" would educate people and preemptively answer questions such as yours about why a $5 million exit nets $0 for employees.