Newbie question

I have installed OpenVPN Connect and I have an .ovpn config file and a ca.crt file.
How do I get the certificate entered and activated?

Where did you get your certificate ?

From my Synology NAS. The PC is Windows 10.

You can probably inline the certificate into the config file.
https://community.openvpn.net/openvpn/wiki/Openvpn24ManPage#lbAW

<ca>
paste the file here
</ca>