I was few days away, thanks for reply to this thread. 
OS Version:
[root@agsstr01 ~]# lsb_release -d
Description: CentOS release 6.9 (Final)
[root@agsstr01 ~]#
Node version:
[root@agsstr01 ~]# node --version
v8.11.1
[root@agsstr01 ~]# npm --version
5.6.0
╭─────────────────────────────────────╮
│
│ Update available 5.6.0 → 6.0.1
│ Run npm i -g npm to update
│
╰─────────────────────────────────────╯[root@agsstr01 ~]#
Should my OS, nodejs and nmp version match?
It seems that there is a update for npm from V. 5.6.0 to 6.0.1
Readme says that npm V 5.0 or abve is needed. I can try to upgrade npm an run the setup again.
Thanks,
Daniel