Build Error : "You must use shadow build (e.g. mkdir build; cd build, qmake ../qgroundcontrol.pro)

Hello
I am trying to solve the following error message.
I have no idea how to solve it.
Please help me.

Development Environment : Qt Creator on Ubuntu

Build Error : "You must use shadow build (e.g. mkdir build; cd build, qmake …/qgroundcontrol.pro).