A Clarification
Irrigation Vaiants
Water application amounts and run times will vary according to several factors
The Soil or Grow Media
The plant "water use type".
Whether there is a "Pre-Set Runtime
If "Less than Optimum" moisture depth is selected

There are three different water quantities specified:

1st - The amount that will be supplied if the emitter count and run time specified are followed
This is a calculation based on emitters multiplied by time, and varies from optimum as a fraction of an emitter is not possible, and rounding off must occur.

2nd - The amount that is technically required for optimum outcomes.
3rd - The amount needed if watering a completely dry soil

With proper irrigation, water is reapplied before plants wilt.
So, there will already be some moisture in the soil when a new irrigation begins.

Drought tolerant plants should have dryer soil than Heavy water use plants when it is time to reapply moisture. Therefore; though requiring irrigation less often, will need a bit more water when irrigated.

Due to these factors, the calculator specifies the different quantities of water. If watering a new plant with dry soil, then use the quantity of water specified for that, or run an extra manual start for the regular optimum run time.

(how many minutes / gallons)
Remember "how many minutes" varies with the number and flow rate of the emitters you use.
Most emitters are rated in gallons or fractions of a gallon per hour

As shown here; 1/4 inch dripperline has "built-in" 0.75 gallon per hour emitters.
These are evenly spaced every 6 or 12 inches depending on which style used.
By cutting a specified length then adding a plug at the far end, you will get the correct number of emitters needed for the pot being watered.