This is my compose file:

:::spoiler compose.yaml

volumes:
  db:

services:
  db:
    image: mariadb:10.6
    restart: always
    command: --transaction-isolation=READ-COMMITTED --log-bin=binlog --binlog-format=ROW
    volumes:
      - db:/var/lib/mysql
    secrets:
      - mysql_root_password
      - mysql_nextcloud_password
    environment:
      - MYSQL_ROOT_PASSWORD_FILE=/run/secrets/mysql_root_password
      - MYSQL_PASSWORD_FILE=/run/secrets/mysql_nextcloud_password
      - MYSQL_DATABASE=nextcloud
      - MYSQL_USER=nextcloud

  nextcloud:
    image: nextcloud
    restart: always
    ports:
      - 8080:80
    depends_on:
      - db
    links:
      - db
    volumes:
      - /var/www/html:/var/www/html
      - /srv/data:/srv/data
    secrets:
      - mysql_nextcloud_password
    environment:
      - MYSQL_PASSWORD_FILE=/run/secrets/mysql_nextcloud_password
      - MYSQL_DATABASE=nextcloud
      - MYSQL_USER=nextcloud
      - MYSQL_HOST=db

secrets:
  mysql_root_password:
    file: ./secrets/mysql_root_password.txt
  mysql_nextcloud_password:
    file: ./secrets/mysql_nextcloud_password.txt

:::

You can access it on port 8080 and perform the initial setup manually. For the database server address, use the db hostname. You’ll have to use a reverse proxy for HTTPS.