how much is required for a patch in my driveway approximately 2 inches deep by 2' x 2' irregular shape

For something that size I would use regular concrete mix - much less expensive. Be sure to moisten the existing surface prior to repair. Cover with plastic and let "cure" for a day.

It would take roughly 8 of the 10 lb pails to repair that area. Maybe a little less, but better to have more and not need it than to need it and not have it. Just return any of the unused pails.