Connect v3 is quite a different program from Connect v2. It doesn't upgrade v2 to v3. It's a separate program. So no importing of data happens.
At the moment Connect v3 has almost all of the features that Connect v2 had, but also a bunch of new features. One thing missing however is command line support. This is coming in a future release of Connect v3. With that version, it will be possible to use the command line to script importing files.
You can use command line tools on Access Server to generate installer files for OpenVPN Connect v2 or v3 with a profile already bundled inside of it. You just install that and you're done. Profile already present. I would recommend doing that. You can find that information here:
https://openvpn.net/vpn-server-resources/create-connection-profiles-and-connect-client-installers/#OpenVPN_Connect_Client_installer_creation