Because this is 5.15.2, not a commercial LTS version, you are entitled to no official support from The Qt Company. The community (via Qt Forum, Stack Overflow, or Reddit/r/QtFramework) is your only lifeline.
Why is qt-opensource-windows-x86-5.15.2.exe so frequently searched and downloaded? The answer lies in the timing of its release. qt-opensource-windows-x86-5.15.2.exe
This created a unique dynamic: