Absolutely not! All the necessary geometry node parameters are available in the Modifier stack. You can use the sliders or directly input values. As far as the nebula shaders go, if you have a moderate amount of shader node experience, you'll be fine. Full usage instructions are provided in the pdf file in the product zip.

For the sake of staying relatively up to date, I've made Blender 3.6 LTS the minimum requirement. It hasn't been tested in earlier versions.

I focus on Cycles. You *can* produce images using Eevee but they will look far superior using Cycles.