First, go to the Mod Range tab on Steam Engine. Select your mod from the APV dropdown list. If your mod isn't listed, choose one that's close and then modify the values associated with it to match your mod. You may need to research the specs of your mod to find those values.
Now adjust the Max Power value to what power that you actually intend to use. For example, on a mod that's capable of 100W, you probably should adjust it down to 30-60W. Why would you use less power than the mod can do? Because of power efficiency and to limit the overall amount of heat that your rda/rta can handle based on airflow and configuration. For example, 80+W is too much heat for a lot of rta tanks to handle with limited airflow, reduced chamber size, and small decks. An rda with a large deck, huge airflow, and heat sink fins can handle and control more heat to keep the vape from being way too hot.
After adjusting the max power, the Steam Engine page will show a calculated sweet spot resistance. Use that as a guideline for the coil build. On some mods the sweet spot will be subohm, on others it will be >1 ohm. On the Sig 100, it will probably be a subohm value.
On the Coil Wrapping tab you can plug in that sweet spot resistance and change the Heat Flux watts to the max that you used on the Mod Range page. Now you can use the Heat Flux icon color to get a coil build that show bright green at around 200 mW/mm². The actual dimensions of the coils should be targeted based on the air flow size and location. A coil that is much longer, shorter, thicker or thinner than the airflow won't vaporize efficiently. Coils with small diameters will support less juice flow and hold less juice inside the coil.
If a coil has too many wraps to be practical, increase the internal diameter. If the internal diameter start getting too big, change the size of the wire or go to parallel/twisted wire builds.
After reading this description, perhaps you can see how the mod and atty that you use are major factors to find a suitable coil build. The power and heat flux are important to control the vaporization temperature range and power efficiency. The airflow and wicking affect the dimensions of the coil within these other factors.