I see lots of errors and suggestions about Parent module \'\' not loaded, ...
I don\'t see any about specifically "out of the box" django 3.5.<
I had a similar issue. I think it is the Django version you installed with pip. For me combination of Python3.5 and Django 1.9 did not give me that error.
$ rm -r /home/isaac/.virtualenvs/foobar #Remove the content
$ /usr/bin/python3 -m venv /home/isaac/.virtualenvs/foobar #Recreate your environment
$ cd /home/isaac/.virtualenvs/foobar
$ source bin/activate #Activate the environment
$ pip -V #(my version is 8.1.1 -> 20.x ==current version)
$ pip install django==1.9 #That version did not give an teh error
$ django-admin startproject yourprojectname #(worked nicely)
Alternative: Upgrade your Python version >= 3.6 on your Ubuntu machine and your're ready to go with the latest Django version Here!