I struggeled to get Maxum to work in docker when using traefik. Here is my solution (i know its not pretty but i hope it helps someone)
so my domains are maxun.mydomain.com for frontend and maxun-api.mydomain.com for backend.
I have copied the browser folder from the project to /root/docker-containers/maxun/browser
/root/docker-containers/maxun/.env - env.txt
/root/docker-containers/maxun/docker-compose.yml - docker-compose-maxun.yml
/root/docker-containers/traefik/docker-compose.yml - docker-compose-traefik.yml
docker-compose-maxun.yml
docker-compose-traefik.yml
env.txt
in maxum docker-compose.yml search for "REMOVE THIS BLOCK TO ALLOW REGISTRATION" to allow registration