docker-flarum: Can't install flarum

When I click the install flarum button, I keep getting an internal error. I entered mariadb as the MySQL host, flarum as the database and the username and test123 as the password. Is there any way I can get the logs of the server? My docker version is 1.11.1 and the only output I get from the flarum container is:

flarum     | [INFO] First launch, you must install flarum by opening your browser and setting database parameters.

Docker-composle.yml:

flarum:
  image: mondedie/docker-flarum
  container_name: flarum
  links:
    - mariadb:mariadb
  environment:
    - FORUM_URL=http://76.105.7.45:3991
    - DB_PASS=test123
    - DEBUG=true
  volumes:
    - /mnt/docker/flarum/assets:/flarum/app/assets
    - /mnt/docker/flarum/extensions:/flarum/app/extensions

#- /mnt/docker/flarum/config.php:/flarum/app/config.php

mariadb:
  image: mariadb:10.1
  container_name: mariadb
  volumes:
    - /mnt/docker/mysql/db:/var/lib/mysql
  environment:
    - MYSQL_ROOT_PASSWORD=test123
    - MYSQL_DATABASE=flarum
    - MYSQL_USER=flarum
    - MYSQL_PASSWORD=test123

nginx:
  image: wonderfall/boring-nginx
  container_name: nginx
  links:
    - flarum:flarum
  ports:
    - "3991:8000"
    - "443:4430"
  volumes:
    - /mnt/docker/nginx/sites-enabled:/sites-enabled
    - /mnt/docker/nginx/conf:/conf.d
    - /mnt/docker/nginx/log:/var/log/nginx
    - /mnt/docker/nginx/certs:/certs