ERROR: The Compose file ‘/home/wataru/git/rcll-get-started/compose_files/refbox.yaml’ is invalid because: services.refbox.depends_on contains an invalid type, it should be an array

ERROR: The Compose file '/home/wataru/git/rcll-get-started/compose_files/refbox.yaml' is invalid because:
services.refbox.depends_on contains an invalid type, it should be an array

のエラーは，書いてあるとおりcompose_files/refbox.yaml の中身がおかしい．
servicesの中のrefboxの中のdepends_onが配列でないといけない　っていっています．

  refbox:
    container_name: refbox
    image: "${REFBOX_IMAGE}:${REFBOX_TAG}"
    network_mode: "host"
    depends_on:
      mongodb-check:
        condition: service_completed_successfully

ここですね．
mongodb-check は，refboxの手前で用意していますので，

  refbox:
    container_name: refbox
    image: "${REFBOX_IMAGE}:${REFBOX_TAG}"
    network_mode: "host"
    depends_on:
      - mongodb-check:
      # mongodb-check:
      #   condition: service_completed_successfully

としてみましょうか．