Install libpolkit-qt5-1-dev by entering the following commands in the terminal:
sudo apt update sudo apt install libpolkit-qt5-1-dev
PolicyKit-qt5-1 development files
PolicyKit is an application-level toolkit for defining and handling the policy that allows unprivileged processes to speak to privileged processes. . It is a framework for centralizing the decision making process with respect to granting access to privileged operations (like calling the HAL Mount() method) for unprivileged (desktop) applications. . libpolkit-qt5-1 provides convenience classes and methods for Qt/KDE applications that want to use PolicyKit-1. . This package contains the development libraries and headers.