The Ring Doorbell is not Z-Wave, unlike the Ring products that are on the list, nor is there a public, documented API. So, there is no way for Hubitat to integrate, sort of convincing Ring to allow or perhaps create a proprietary integration. You could ask Ring for that, I suppose, but I wouldn't hold my breath. 
However, I do believe there is at least one reverse-engineered community offering. This is totally unsupported by both parties (and could break at any time, etc.), though it appears many are using it successfully now. You can find some discussions in previous threads that have been created on this topic with a search. Here's one: RING Doorbell integration
