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 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 page.