These installers are useful for restricted environments, such as those behind a corporate firewall. Open Source Users (Online Installer/Archive) Online Installer : You can still install Qt 5.15.2 by downloading the Online Installer Maintenance Tool , select the checkbox and click to reveal older versions like 5.15.2. Source Build : If you must install offline, you can download the Source Packages (zip/tar.xz) and compile them manually Command Line Tool (aqtinstall) You can use aqtinstall
If the main server is slow, use official mirrors (China: mirrors.tuna.tsinghua.edu.cn/qt/ , Germany: ftp.fau.de/qt/ ). Always ensure the URL path ends with /5.15.2/ and the filename contains opensource . qt 5152 offline installer