问如何在CircleCI中使用私有存储库？

EN

    #!/bin/bash -eo pipefail
    git clone https://github.com/xxxxxx/lad.git
    Cloning into 'lad'...
    ERROR: Repository not found.
    fatal: Could not read from remote repository.

    Please make sure you have the correct access rights
    and the repository exists.
    Exited with code 128

version: 2

jobs:
  build:
    docker:
      - image: ruby:2.3.0
        environment:
      - LANG: C.UTF-8
    environment:
      BUNDLE_GEMFILE: /root/project/.circleci/Gemfile
    steps:
      - checkout
      - run: git clone --depth=1 --branch=${REDMINE_VERSION:-3.4-stable} https://github.com/redmine/redmine.git
      # this is private repository ↓
      - run: git clone https://github.com/xxxxxx/lad.git
      - run:
          name: Check status
          command: |
            pwd
            ls -al