Once the download is complete, run the offline installer and follow the installation instructions to install Qt 5.15.2 on your system.
However, there are still several ways for open-source users to get this specific version or simulate an offline installation experience. 1. The Official Route (Commercial Users) download qt 5.15.2 offline installer
Official offline installers for Qt 5.15.2 are for open-source users. Starting with Qt 5.15, The Qt Company restricted offline packages to commercial license holders only. Once the download is complete, run the offline