soniktrooth Once I quit docker it was more straight forward and I managed to load the welcome.test and then add a Drupal site to the nginx section of My First Stack. Took me a second to work out where the 'root' was for this Drupal site—turned out it was src/www/web. I installed a db and we were off to the races.
I've had this issue personally in my Laravel projects; numerous times I've configured the Indigo site root as laravel-codebase instead of laravel-codebase/public.
Did you also initially attempt to use the project root rather than the web root? I ask because I've had the idea that I could pretty easily recognise the framework in use, and detect this common mistake and offer to fix it automatically.