Darktable not running on Catalina (Mac)

I switch recently from Mojave to Catalina. When I start dt I get the bouncing logo, but that is all I get. I installed the latest version [darktable-4.2.0_x86_64.dmg]. I thought I might build a version myself from the sources. Installed Homebrew and make. Followed the instruction from the readme to build the program according to:

./build.sh --prefix /opt/darktable --build-type Release --install --sudo

What followed were some errors I can not deal with due to lack of knowledge:
CMake Error at /usr/local/Cellar/cmake/3.25.2/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
Could NOT find OpenMP_C (missing: OpenMP_C_FLAGS OpenMP_C_LIB_NAMES)
(Required is at least version “4.5”)
Call Stack (most recent call first):
/usr/local/Cellar/cmake/3.25.2/share/cmake/Modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
/usr/local/Cellar/cmake/3.25.2/share/cmake/Modules/FindOpenMP.cmake:580 (find_package_handle_standard_args)
CMakeLists.txt:94 (find_package)

I have been using dt for some years now and I like it very much. I have 2 options:
1 a ready installable 64 bit version or
2 my now build. I thought it would be doable, but …

Somebody there to help and guide me to solve this? I am on a Mac late 2012 (Catalina) and my unix experience is very limited.

I don’t know MacOS, but the build log indicates OpenMP is missing, or is the wtrong version. MacOS from 2012 may lack some libraries.

I have read that, but I am at a loss how to get the right version. There is probably a nice unix command for.

I’m not 100% sure. A 10-year-old Linux distribution would not be able to run today’s darktable.

It did run under Mojave, but Catalina is 64 bit en there is a 64 bit version: darktable-4.2.0_x86_64.dmg. I could install this version but it hangs. It give me a bouncing logo at the bottom of the screen, but never comes up with the UI.

Have you given it disk permissions in gatekeeper?

Did you follow the macOS specific instructions and scripts?

I am root while trying to build. Does that answer your question?
What I did after installing Homebrew and make
downloaded source dt
unpack zip file
started bash in terminal with instruction from the readme

darktable provides a shell script that automatically takes care of building on Linux and macOS for classic cases in a single command:
bash-3.2$ ./build.sh --prefix /opt/darktable --build-type Release --install --sudo

Now that I think about it some more, I presume that the program hangs for the same reason as the error in building the program. Once the official dt starts and I get the bouncing logo, the programme is looking for the missing part in the OpenMP library. As it doesn’t found what is needed, it stops (not responding). Maybe once the right OpenMP library is installed, the official version of dt will probably work.

How do I refresh the OpenMP?