Also @gien I use NordVPN myself. They are great, but you may well want to consider using WireGuard rather than OpenVPN. Check out this excellent guide here:
The reason for the above steps is that NordVPN don't release WireGuard credentials. They want everyone to use their own NordLynx built upon WireGuard, but it is easy to extract the relevant credentials as demonstrated above. I think NordVPN are fine with this, they just don't (yet?) officially support WireGuard.