Why Is Ansible Tower Installation failing for being unable to do privilege escalation?

Issue

• Ansible Tower installation tasks are failing for the connecting user on some or all of the nodes for not being able to privilege escalate:

  TASK [preflight : Preflight check - check Tower license type] *******************************************************
  fatal: [xx.xx.xx.xx]: FAILED! => {"changed": false, "module_stderr": "Shared connection to xx.xx.xx.xx closed.\r\n", "module_stdout": "\r\nSorry, user nfvuser is not allowed to execute '/bin/sh -c echo BECOME-SUCCESS-npejzpsicaeqgfccjxndngqqglhipdng; /usr/bin/python /var/tmp/ansible-tmp-1543013552.07-49200751691785/command.py' as awx on anstower3.nfv.cselt.it.\r\n", "msg": "MODULE FAILURE", "rc": 1}
  ...ignoring
  fatal: [xx.xx.xx.xx]: FAILED! => {"changed": false, "module_stderr": "Shared connection to xx.xx.xx.xx closed.\r\n", "module_stdout": "\r\nSorry, user nfvuser is not allowed to execute '/bin/sh -c echo BECOME-SUCCESS-hzfpwatojvgwialqfxnlbesnpfowaylo; /usr/bin/python /var/tmp/ansible-tmp-1543013552.03-156369402050656/command.py' as awx on anstower2.nfv.cselt.it.\r\n", "msg": "MODULE FAILURE", "rc": 1}
  ...ignoring
  changed: [xx.xx.xx.xx] => {"changed": true, "cmd": "awx-manage check_license", "delta": "0:00:02.135646", "end": "2018-11-23 23:52:34.427364", "rc": 0, "start": "2018-11-23 23:52:32.291718", "stderr": "", "stderr_lines": [], "stdout": "enterprise", "stdout_lines": ["enterprise"]}