Cad/Cam software for Linux

I still have 18.04 on my company computer.
I am currently updating my debian10 to Python 3.9 in my VM. Will try it then with Debian!

I now have my debian10 in my VM on Python3.9.1.
Now that I have reinstalled some things and I still have
no matching distribution found for pyqt5-qt5 =5.15.2 (from pyqt5)
at the inatalation of 'viaconstructor' I ran out of memory in the VM.

The last suggestion with:
apt-get install python-matplotlib-data
does not work either ...
 

I must be out of my depth with this!!!

I just do not understand where the problem lies ...

Any time i get the missing QT5 stuff i use PhillC's QT installer included with LinuxCNC, it works always:
forum.linuxcnc.org/qtvcp/38414-installing-qtvcp

I have the directory from:

qtvcp/designer/install_script

NOT on my computer

There are two paths on that tutorial, did you try both?
How did you install LinuxCNC?

yes I have tried both
installed with the ISO 2.8.1 and update to 2.8.3
it runs in a VM