How to configure .condarc for getting package from Nexus repository

By default, when you install a python package, the repository is for example conda-forge.
I have a python library packaged in gitlab CI with a deployment on a nexus repository.

But even if I configure this repo in my .condarc file, i have a 404 http error.

Is there some rules to follow for a correct access ? I read that you must have a reportage.json file in the repository.

Can you help me with that ?
My goal is to do an “import mylibrary” in a python script, with a mamba or conda install before that

Thanks