В контейнерах нет интернета. Так же судя по всему у nginx какие-то проблемы с fpm, если посмотреть в логи, то можно увидеть следующую ошибку:
2020/03/30 15:55:21 [error] 6#6: *4 connect() failed (113: No route to host) while connecting to upstream, client: 10.0.2.2, server: , request: "GET /wpad.dat HTTP/1.1", upstream: "fastcgi://172.18.0.2:9000", host: "wpad.beeline"
Все это крутиться на VirtualBox на CentOS 8, настройки сети следующие:
https://i.imgur.com/apXpS4b.png
nginx/default:
server {
     listen 80;
     index index.php index.html;
     root /app/public;
     location / {
         try_files $uri /index.php?$args;
     }
     location ~ \.php$ {
         try_files $uri =404;
         fastcgi_split_path_info ^(.+\.php)(/.+)$;
         fastcgi_pass manager-php-fpm:9000;
         fastcgi_index index.php;
         include fastcgi_params;
         fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
         fastcgi_param PATH_INFO $fastcgi_path_info;
     }
 }
nginx.docker:
FROM nginx:1.17.9-perl
COPY ./nginx/default.conf /etc/nginx/conf.d/default.conf
WORKDIR /app
php-cli.docker:
FROM php:7.4-cli
RUN apt-get update && apt-get install -y unzip
WORKDIR /app
COPY ./ ./
php-fpm.docker
FROM php:7.4-fpm
WORKDIR /app
docker-compose.yml:
version: '3'
services:
  manager-nginx:
    build:
      context: ./manager/docker/development
      dockerfile: nginx.docker
    volumes:
      - ./manager:/app
    depends_on:
      - manager-php-fpm
    ports:
      - "80:80"
  manager-php-fpm:
    build:
      context: ./manager/docker/development
      dockerfile: php-fpm.docker
    volumes:
      - ./manager:/app
  manager-php-cli:
    build:
      context: ./manager/docker/development
      dockerfile: php-cli.docker
    volumes:
      - ./manager:/app
Если в php-cli.docker добавить
RUN apt-get update && apt-get install -y unzip
то будет ошибка с пакетным менеджером 
Reading package lists...
W: Failed to fetch http://deb.debian.org/debian/dists/buster/InRelease  Temporary failure resolving 'deb.debian.org'
W: Failed to fetch http://security.debian.org/debian-security/dists/buster/updates/InRelease  Temporary failure resolving 'security.debian.org'
W: Failed to fetch http://deb.debian.org/debian/dists/buster-updates/InRelease  Temporary failure resolving 'deb.debian.org'
W: Some index files failed to download. They have been ignored, or old ones used instead.