How to Properly setup cmake library

project on github
I am new to cmake and I am having trouble trying to figure out how to setup a library project. The issue is that I am not able to include the libraries header files in projects that use the library. For example, my project in ./test/src/main.cpp is not able to include ./include/log.hpp. The source file ./src/log.cpp can include ./include/log.hpp.

see Using PUBLIC FILE_SET HEADERS with dependent targets - #5 by ClausKlein