OpenVPN Connection Error: "Cannot ioctl TUNSETIFF tun: Operation not permitted (errno=1)"

Hi, I want to connect my project using OpenVPN. Last time i tried using pritunl-client it doesn’t working because i cannot write in /var/run/pritunl.auth. I wonder if pkgs.openvpn got the same error because it doesnt have write access too. How to resolve this problem? or How to gain credentials to write the like sudo or other ways to modify the permission?

Thanks,
Avei