Test of the question: https://stackoverflow.com/questions/45867580/download-public-dropbox-file-with-qt

downloader.cpp

#include "downloader.h"

Downloader::Downloader(const QUrl &url, QObject *parent) : QObject(parent)
{
    auto manager = new QNetworkAccessManager(this);
    QNetworkRequest request(url);
    connect(manager, &QNetworkAccessManager::finished, this, &Downloader::replyFinished);
    manager->get(request);

}

void Downloader::replyFinished(QNetworkReply *reply)
{
    QUrl redirect= reply->attribute(QNetworkRequest::RedirectionTargetAttribute).toUrl();
    if (!redirect.isEmpty() && redirect.isValid() && reply->url() != redirect){
        qDebug()<<redirect;
        if(redirect.isRelative())
            redirect = reply->url().resolved(redirect);
        reply->manager()->get(QNetworkRequest(redirect));
        return;
    }

    qDebug()<<"finished";
    const auto newVersion = QString(reply->readAll());
    qDebug()<<newVersion;
}

downloader.h

#ifndef DOWNLOADER_H
#define DOWNLOADER_H

#include <QNetworkReply>
#include <QObject>

class Downloader : public QObject
{
    Q_OBJECT
public:
    explicit Downloader(const QUrl &url, QObject *parent = nullptr);

public slots:
    void replyFinished(QNetworkReply *reply);
};

#endif // DOWNLOADER_H

DropboxDownload.pro

QT += core
QT -= gui

QT += network

CONFIG += c++11

TARGET = DropboxDownload
CONFIG += console
CONFIG -= app_bundle

TEMPLATE = app

SOURCES += main.cpp \
    downloader.cpp

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

HEADERS += \
    downloader.h

main.cpp

#include <QCoreApplication>

#include "downloader.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QUrl url("http://www.dropbox.com/s/ehoawgm89yz6pib/version.txt?raw=1");

    Downloader downloader(url);
    return a.exec();
}

Output:

QUrl("https://www.dropbox.com/s/ehoawgm89yz6pib/version.txt?‌​raw=1") 
QUrl("https://dl.dropboxusercontent.com/content_link/qdWtaff‌​w8D12BrSySNkxdVxNyEg‌​GhAUJcmvLQjOggXVxDuC‌​EfaPWoBdnri75kfnC/fi‌​le") 
 finished 
"2017.09.01\n"`