Could you explain the purpose of the -skip qtwebengine and -skip qtconnectivity flags in the doconfig.bat file? Are those modules particularly difficult to build, or are they just not needed for most open-source projects?
QtWebEngine has a lot of dependencies and is difficult to build because of that. I don't need an embedded browser in my applications, so I didn't include it in the build. QtConnectivity is mostly useful for embedded systems, since it supplies support for Bluetooth and NFC (near field communication), something I don't need in my desktop apps.

If you need one of those, then if the configure script can't find some dependency, it will fail and tell you what it can't find. You either need to find that package (and possibly also build it from source) and tell CMake where to find it or use an implementation provided in the Qt distribution. This is what I did for "zlib" with the config option "-qt-zlib". Refer to Qt's documentation on building from source for some of these configure options.