OpenVPN Prolbem

Hello, First of all, I am totaly new to ubuntu server.
I try to follow digitalOcean guide set up an openvpn server, link is here
but I don’t know why after I try to connect to vpn server, it comes out this

:OpenVPN 2.4.3 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [PKCS11] [MH/PKTINFO] [AEAD] built on Jul 3 2017
: library versions: OpenSSL 1.0.2g 1 Mar 2016, LZO 2.08
:NOTE: the current --script-security setting may allow this configuration to call user-defined scripts
:OpenSSL: error:0906D06C:PEM routines:PEM_read_bio:no start line
:OpenSSL: error:140AD009:SSL routines:SSL_CTX_use_certificate_file:PEM lib
:Cannot load inline certificate file
:Exiting due to fatal error

so anyone can give me some tips what is the problem cause this?
thank you

I’ve moved this to the https://community.ubuntu.com/c/support-help-requests category because this site isn’t designed to take tech support questions. Sorry. I’d recommend using one of the official support channels listed on the https://community.ubuntu.com/t/finding-help/712 page.