OK the difference between my VM and your server is that I run as root, you as admin, and my jupyterlab folder belongs to admin and yours to root.
Try:
chown -R admin: /opt/jupyterlab
cd /opt/jupyterlab
pipenv shell
pip install numpy
As to why your directory does not belong to the same user, I don’t know.
Edit post-solution:
The matter is also discussed on Github: jupyterlab_ynh #35
There may be issues with multi-users with my solution.