Dear Community

I am a complete newbie and after decades I want to switch from BASIC to C++ using 'Qt for Android'.
After reading a C++, as well as Qt manual, a first desktop application starts flawlessly.

Unfortunately, however, I can by no means say the same about setting up Android support.

For two weeks now I've been sitting at it and have already tried everything possible, but it just doesn't want to work the way it's supposed to.

Installed is currently:

JDK 1.8.0_291
NDK r21e
Android OpenSSL Master

... via SDK Manager:

Android SDK Tools (Obsolete) 25.2.5 (this was a suggested solution from the net)
Android SDK Platform Tools 31.0.2
Android SDK Build-tools 26-30.0.3
Android 11
Android R - SDK Platform Android R Preview
Android 10
Android 4.4.2

... via the Maintainance Tool:

Qt 6.1.1
Qt 5.15.2
almost all 'Developer and Designer Tools'.

Under Settings>Devices, 'Platform-SDK is installed' and 'For all installed Qt versions, all necessary packages are installed' are shown as incorrect.

The resulting generated dialog shows the following missing packages in the Android SDK installation:

extras;google;usb_driver, so exactly the ones I installed manually?!

Under Kits>Qt versions, all 'Qt 6' applications as well as 'Qt 5.15.2 for Android' show the following error:

'No compiler can generate code for this Qt version. Please set up a compiler suitable for [...] unknown-linux-android-elf-unknown'.

By the way, my system is Windows 7, x64.

It would be really fantastic if someone could help me before I throw the computer out the window. :-)

Many greetings from Switzerland