How to set up a VPN client on a VPS?

Question

openvpn

Good afternoon.
I'm doing a project that requires interaction with a client API.
I'm developing a project locally, the client gave me access to his VPN.
I am working on a Linux platform.
I use FortyClient SSL VPN as a VPN client.
The customer gave me the following parameters:
1.Server
2.Port
3.Username
4.Password

I'm making deployments to a test server, and I don't know how to set up a VPN here.
Installed OpenVPN client, but it requires ca.cert.
Where to get it? Any help will be glad.
Here is the openvpn configuration

Here it says it requires CA