Convert apc certificate for OpenVPN

Hello

I'm trying to connect a RouterOS device (client) to a UTM9 gateway (server) using OpenVPN. I have created the connection and downloaded the certificates, but they are in .apc format. While the RouterOS device imports these it throws an error, I think because it doesn't realise there is a key in the file.

Is there any way to convert from the .apc file I downloaded from UTM9 to the discrete certificates expected by OpenVPN?

Thanks
Giles.