.\qt-unified-windows-x64-online.exe --mirror https://mirrors.tuna.tsinghua.edu.cn/qt/
If you are using this installer to build new applications, keep these migration barriers in mind:
Since the offline installer is inaccessible, open-source developers must install Qt 5.15.2 using the online installer tool. The process is well-documented but can be challenging due to the advanced age of this version.