I did it while staying at Riviera back in January. I think they have more than one hunt. The one I did had a few things to find at Riviera, but mostly was for things at the EPCOT resorts. Hence Skyliner Scavenger Hunt. Most things were fairly easy to find, but a couple were kind of hard, especially the BWV lobby one (at least for me).
IIRC, it had a 2 hour time limit, was offered maybe 2 or 3 days a week, and had a morning and afternoon time.
I enjoyed it, especially if you happen to have a non-park day and are looking for something to do.
I wonder if they are currently offering it as they seem to have cancelled most activities.