Try to add these line in your cmake file:
set(CMAKE_PREFIX_PATH ${ROOT_INCLUDE_DIRS} ${ROOT_LIBRARY_DIR})
find_dependency(Vdt)
or try to set the VDT_INCLUDE_DIR and VDT_LIBRARY values to point to ${ROOT_INCLUDE_DIRS} and ${ROOT_LIBRARY_DIR}/Vdt (or whatever the Vdt library name is, I can’t try, there is no Vdt on Windows…)