[SOLVED] CMake Errors while configuring

Hey there!

I am facing problems that I am not able to solve myself. I am working on Ubuntu 20.04.3 LTS and want to use Sofa including the CGAL and SofaPython3 Plugins.
As the CGAL Plugin is not included in the binaries, I decided to compile Sofa with CMake following the steps of the User documentation.
Now CMake is throwing the following errors during Config stage:

Adding plugin SofaPython3
Found PythonInterp: /usr/bin/python3.8 (found suitable version “3.8.10”, minimum required is “3.7”)
Python:
Version: 3.8.10
Executable: /usr/bin/python3.8
Headers: /usr/include/python3.8
Libraries: /usr/lib/x86_64-linux-gnu/libpython3.8.so
User site: /home/tori/.local/lib/python3.8/site-packages
pybind11:
Version: 2.4.3
Config: /usr/lib/cmake/pybind11/pybind11Config.cmake
Fetching external subdirectory SofaPython3
CMake Error: File /home/tori/sofa_21/src/applications/plugins/SofaPython3/ExternalProjectConfig.cmake.in does not exist.
CMake Error at SofaKernel/modules/Sofa.Config/cmake/SofaMacrosConfigure.cmake:234 (configure_file):
configure_file Problem configuring file
Call Stack (most recent call first):
SofaKernel/modules/Sofa.Config/cmake/SofaMacrosConfigure.cmake:279 (sofa_add_generic_external)
applications/plugins/CMakeLists.txt:34 (sofa_add_subdirectory_external)

CMake Error at SofaKernel/modules/Sofa.Config/cmake/SofaMacrosConfigure.cmake:236 (file):
file COPY cannot find
“/home/tori/sofa_21/src/applications/plugins/SofaPython3/ExternalProjectConfig.cmake.in”:
No such file or directory.
Call Stack (most recent call first):
SofaKernel/modules/Sofa.Config/cmake/SofaMacrosConfigure.cmake:279 (sofa_add_generic_external)
applications/plugins/CMakeLists.txt:34 (sofa_add_subdirectory_external)

Pulling …
CMake Error at SofaKernel/modules/Sofa.Config/cmake/SofaMacrosConfigure.cmake:262 (message):
Failed to add external repository SofaPython3.

See logs in
/home/tori/sofa_21/build/external_directories/fetched/SofaPython3/logs.txt
Call Stack (most recent call first):
SofaKernel/modules/Sofa.Config/cmake/SofaMacrosConfigure.cmake:279 (sofa_add_generic_external)
applications/plugins/CMakeLists.txt:34 (sofa_add_subdirectory_external)

CMake Error: File /home/tori/sofa_21/src/applications/plugins/SofaPython3/ExternalProjectConfig.cmake.in does not exist.
CMake Error at SofaKernel/modules/Sofa.Config/cmake/SofaMacrosConfigure.cmake:269 (configure_file):
configure_file Problem configuring file
Call Stack (most recent call first):
SofaKernel/modules/Sofa.Config/cmake/SofaMacrosConfigure.cmake:279 (sofa_add_generic_external)
applications/plugins/CMakeLists.txt:34 (sofa_add_subdirectory_external)

CMake Error at SofaKernel/modules/Sofa.Config/cmake/SofaMacrosConfigure.cmake:271 (add_subdirectory):
The binary directory

/home/tori/sofa_21/build/applications/plugins/SofaPython3

is already used to build a source directory. It cannot be used to build
source directory

/home/tori/sofa_21/src/applications/plugins/SofaPython3

Specify a unique binary directory name.
Call Stack (most recent call first):
SofaKernel/modules/Sofa.Config/cmake/SofaMacrosConfigure.cmake:279 (sofa_add_generic_external)
applications/plugins/CMakeLists.txt:34 (sofa_add_subdirectory_external)

Adding plugin LMConstraint
SofaDistanceGrid not found: DistanceLM codes will not be compiled
Adding application runSofa
Write Plugin list at /home/tori/sofa_21/build/lib/plugin_list.conf.default
Configuring incomplete, errors occurred!
See also “/home/tori/sofa_21/build/CMakeFiles/CMakeOutput.log”.

I tried it several times from scratch but I am not able to solve these issues.
Any help is highly appreciated!

Many thanks!
Best regards,

Tori