Building on M1 computer failed: CMake warning: unsupported CMAKE_SYSTEM_PROCESSOR 'arm64'

[thinium]

When I run this command: CC=/usr/bin/clang CXX=/usr/bin/clang++ cmake -DCMAKE_BUILD_TYPE=Debug ../
I get the following warning:

CMake Warning at cmake/target_optimizations.cmake:57 (message):
  unsupported CMAKE_SYSTEM_PROCESSOR 'arm64'

Does that mean arm64 architecture is not supported by the make file? I have zero experience with modifying makefile, but what are the necessary changes to make it build for arm64? Thank you!