ERROR! the role 'openwisp.openwisp2' was not found in /home/etudiant/openwisp2-ansible-playbook/roles:/home/etudiant/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:/home/etudiant/openwisp2-ansible-playbook

The error appears to be in '/home/etudiant/openwisp2-ansible-playbook/playbook.yml': line 4, column 9, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:

  roles:
      - openwisp.openwisp2
        ^ here