The CanAm (red) you are referring to is owned by a relative of one of "THE" families in the city. You can't get or/cr's for atv's. 20 plus years ago you could. So unless you find an old one and restore it you can just take your chances....
I have seen ATVs (all terrain vehicles) riding around Dumaguete as well. Some have plates, other's do not. I suspect that the ones that are legal have had turn signals and plate holders installed to make them road legal. The others I suspect just drive around as they please as there is no law enforcement in the Philippines. Most of the four-wheelers I have seen in Dumaguete are of Chinese origin. There have been a few of those for sale on the forum in the past.