Almost every delivery that goes badly goes badly for one of three reasons, and all three are things you can check yourself a week ahead with no equipment at all.
Space first. An inflatable needs clear ground with room left over on every side — not just the footprint of the unit, but a margin around it and clear air above it. Look up as well as down: a low branch or a power line over the spot rules it out, and so does a fence close enough that a slide would land against it.
Then the surface. Flat, reasonably level ground is what you want — grass is ideal, a clean patio or driveway is fine. What causes trouble is a slope, loose gravel, sprinkler heads, or anything sharp in the grass. Have a walk over the spot and pick up what shouldn't be there.
Last, power. The blower has to run for the entire time the unit is up, from an ordinary outdoor outlet the cord can reach. If the only outlet is on the far side of the house, say so when you book rather than on the day — that is the single most common reason a set-up stalls.
Access counts too: we have to get the unit from the truck to the spot, so a gate that opens wide enough and a path that isn't blocked make the difference between a twenty-minute set-up and an hour.