WiFi & captive are a completely separate thing from their router product line. The access points are called UniFi, I'd suggest the "AC Pro" variant for home use. One unit should do it, unless you've got a big mansion, then maybe 2 or even more might be needed to cover all floors etc.
The APs are powered via PoE, so unless you have a PoE capable switch, just use the supplied adapter that plugs into power and your local network and runs one network cable to the AP. After connecting the AP to your network you can either use the mobile app to configure it or install the UniFi controller software on some continuously running machine, either in your local network or somewhere on the internet (I have a controller running on an AWS micro tier server). Note that if you want to use the "Guest Network" (=Captive Portal) you need the controller software.
UniFi Controller demo: https://demo.ubnt.com/manage/site/default/dashboard