Indeed, you need to have a License in order to use Substance and there are plenty of tutorials on Yt that can help you to get better at blender.
Now the best way to preview/reload your textures in XP11 is using the Texture Browser tool that allows you to reload any texture that is currently loaded in your flight
You can access it via the top menu while inflight going Developer>Show Texture Browser
Once opened you can browse for any texture you'd like using the search bar, keep in mind that it is case sensitive so if you can't find your texture it might be due to that
After you find the texture you want to reload just double click over it, a new window will pop out and click reload
And that's it!