That is not correct. For this addon creating 10 different assets ( from 0,1,2,...9) is easier than creating 36 assets so the person who created them (i just updated them to work in game) created 0 separately so you put 0 + 2 if you want runway 02.
In Real Life it depends on where your location is.. E.g Washington DC Ronald Reagan Airport has Runway 4 and Runway 1. On the other hand Amsterdam Schipol has 06, 09 etc.
As in the screenshots you can see #2 and #02 also this addon is outdated my advice to you to use Vasimir22's runway numbering addon if you want better numbers.

instead of runway 2, it should be runway 02.