Should be easy to get working. Might work out of the box with the GE Link bulb device type if it’s using the Home Automation profile. If they went with the Light Link profile like Hue, then it would just need a few changes.
Either way, it shouldn’t take long to get working with this community!
(ActionTiles.com co-founder Terry @ActionTiles; GitHub: @cosmicpuppy)
Try pairing it with a Philips Hue Bridge (that’s currently how I’m using all my GE Link bulbs). Perhaps not the most directly solution, but those bridges are practically free on eBay if you don’t already use Hue.
If the Cree Bulbs are using the ZigBee “Light Link” profile, they should be compatible with SmartThings, AFAIK, unless they are on some non-supported channel / frequency.