Because Microsoft only issues the OS with basic drivers and some laptops need an app to enable WiFi what you wrote does happen.
Finish the install with drivers for motherboard, audio, video, WiFi, Ethernet then check if your laptop requires an APP to turn on WiFi.
I got a laptop recently and just the other day, I was able to install Windows 7 onto it. Now it won't connect to WiFi. I open up the WiFi thingy on the taskbar and there are no available WiFi networks (not even my neighbor's WiFi). I have tried plugging an Ethernet cord into it and I am not entirely sure what to do from there. Can someone please help? It's a Dell latitude E6420 if that's important.