Problem with automx2 - error setupvenv.sh

[Eric DUVAL]

Hello,

I try to install automx2 on ubuntu LTS 16.04.6 (xenial)
I have read doc: 
https://gitlab.com/automx/automx2/blob/master/doc/installation.adoc

On ubuntu i installed python3.8.2 and pip3 8.1.1.

When i run : sudo su automx2 ./setupvenv.sh i have an error:

Error: Command '['/var/www/automx2/venv/bin/python3', '-Im', 
'ensurepip', '--upgrade', '--default-pip']' returned non-zero exit status 1

Can you help me?

Regards
Eric DUVAL