I understand from the below that concrete is the best sub-surface to install the tiles on. But I have a few other related questions. How thick should the concrete sub-surface be? How do I ensure that the tiles do not slip/move over time?

The typical concrete slab thickness is 4", but there is no standard thickness needed under our Outdoor Basketball Court Kits. The weight of the tiles in conjunction with the pegs on the bottom of the tiles will help them stay in place while at play. There would be no need to add any glue or tape under the tiles to keep them in place.