Download_DEPS option won't be on by default

As your CMakeLists.txt are written now the default option for DOWNLOAD_DEPS won't work. This is because the incorrect syntax in call option(DOWNLOAD_DEPS ON). Cmake will think that ON is the helper text and default value is not provided so it sets it to OFF. To avoid that you have to provide helper text, i.e. call option(DOWNLOAD_DEPS "this option enables automatic downloads of dependencies" ON). See https://cmake.org/cmake/help/v3.23/command/option.html