The process of linking XO files via v++ and the system.cfg is covered in depth in the following two tutorials. For this tutorial these steps are handled by the provided makefile and you will review only the highlights.
https://github.com/Xilinx/Vitis-Tutorials/tree/master/AI_Engine_Development/Feature_Tutorials/05-AI-engine-versal-integration
https://github.com/Xilinx/Vitis-Tutorials/tree/master/AI_Engine_Development/Design_Tutorials/03-beamforming/Module_04_AI_Engine_and_PL_Integration