Get and install vcpkg
Then run vcpkg.exe install mongo-cxx-driver:x64-windows this drags in many boot libraries.
use vcpkg.exe list to see the installed packages
Then do vcpkg.exe integrate install to make the package available to all users.
Open the QtHotelReservationSystem.pro project file and adjust the location of the vcpkg directory.
Now open QtCreator and open the Project by opening the QtHotelReservationSystem.pro file.
Build the project.
Open a console and cd to the build... directory where the QtHotelReservationSystem.exe file was created.
You now need to add the shared .dll libraries with the special QT tool:
c:\Qt\5.11.1\msvc2017_64\bin\windeployqt.exe .
and
copy c:\Users\Richa\Documents\vcpkg\packages\mongo-cxx-driver_x64-windows\bin\mongocxx.dll .
copy c:\Users\Richa\Documents\vcpkg\packages\mongo-cxx-driver_x64-windows\bin\bsoncxx.dll .
copy c:\Users\Richa\Documents\vcpkg\packages\libbson_x64-windows\bin\libbson-1.0.dll .
copy c:\Users\Richa\Documents\vcpkg\packages\mongo-c-driver_x64-windows\bin\libmongoc-1.0.dll .
Good luck!