Before your C++ project can be distributed to users, it must be properly built. Building a project ensures that all content and code, including all necessary libraries, is up to date, in the proper format, and the proper location to run on the desired target platform.
More on working with the Project Build tool in UNIGINE 2: https://l.unigine.com/r3vNVF6sB
Download UNIGINE 2 SDK: https://l.unigine.com/ZMYV2tm8U