@carstenhaubold is it possible that the installation does not use a proxy setting while installing? Other installations would have no problem using the defined proxy.
create_env.err
critical libmamba Download error (6) Couldn't resolve host name [https://conda.anaconda.org/conda-forge/win-64/ca-certificates-2023.5.7-h56e8100_0.conda]
Could not resolve host: conda.anaconda.org