I tried to set it up the other day and failed as well. Looking at their docker-compose examples for reverse proxy, there are a lot of environment variables not included in their original example. After adding all those variables, the container started with a message about first registration.
I haven't tested more than that yet.
EDIT: Added it to my reverse proxy and was able to create the first account via Element.
That absolutly depends on the type and quality of the rice.