Using the officially available online installer qt-unified-windows-x64-4.5.2-online.exe - which is now downloaded from the product site I have tried to set up everything for the latest version 5.15.2 LTS under 32 bits under MSVC 2019. In particular, I was interested in the QPDF module with its Qt* classes and capabilities. Because to compile for the current actual development branch 6.3. * under 32 bits I failed - it was logical to assume that the previous version SHOULD work and provide access to these features by default in all pre-compiled binaries AS-IS, w/o any "special" movements. After a successful installation I made an attempt to build a program that will use the features of the QPdfDocument class, AND it was suddenly discovered that THERE is nothing by default in "successfully" ended-up setup that would allow this module and work with these classes... In the folder .\include simply no corresponding H-files!!!
Somebody - do so, for God’s sake, that at least somewhere we can JUST download and JUST turn on the use of these entities! So that I just entered #include <QPdfDocument>, + turned on the module in the project properties: QT += pdf - and it all worked!!!

FIX this LTS!!!! build for that simple task!