Windows 10 or iPad howto cast to Chromecast

I’m not familiar with the intricacies of remote connect, but I think it works the other way around… you have to pair things on on the local network tablo is, or will be, running. Since you have to configure ports and such on the local network and/or router… then move it to a different network on a different router, just seems flubbed up. Hope I’m mistaken.