AirGroup works without ClearPass, you just won't be able to get as granular with policy restrictions. You'll only be able to limit by role or VLAN.
You need AOS 6.3 or higher for AirGroup which includes support for mDNS devices. To support all other devices (non-Apple), like chromecasts, which use standards based UPnP/SSDP, you'll need AOS 6.4
There was a 6.1 release that supported AirGroup a few years ago, but it is now baked into the mainline releases.