Installed Qt 5.12.1 with MinGW 64bit and path to compiler/debugger are wrong by default

I installed Qt 5.12.1 with online installer and created a new default widget application.

The project can't be compiled, got this error:

Bestimme Windows Runtime-Gerät.

winrtrunner.exe konnte nicht gefunden werden.

Project ERROR: Cannot run compiler 'g++'. Output:

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Maybe you forgot to setup the environment?

Fehler beim Auswerten der Datei D:\xxx\Documents\Qt\xxx\xxx.pro. Abbruch.