Crash probably a couple seconds later, wouldn't rely on the video for the exact timing.
So it seems that ATC made an error by allowing the truck to cross, and then the order to stop wasn't communicated clearly enough. I wouldn't place much blame on the truck.
Edit: Looking at some other videos with that audio, I'm also not sure if the video I linked represents the time between communications correctly, transmission at 3:15 may have been right after the one at 3:02. Anyway, the best thing is to wait for the investigation.
Timestamps from the video:
2:46 Truck requests crossing
2:51 ATC allows it to cross
2:53 Truck confirms
2:58 ATC: "Frontier 4195 stop there please"
3:02 ATC: "stop stop stop stop truck one stop stop stop"
3:15 ATC: "tower, truck one, stop, ..."
Crash probably a couple seconds later, wouldn't rely on the video for the exact timing.
So it seems that ATC made an error by allowing the truck to cross, and then the order to stop wasn't communicated clearly enough. I wouldn't place much blame on the truck.
Edit: Looking at some other videos with that audio, I'm also not sure if the video I linked represents the time between communications correctly, transmission at 3:15 may have been right after the one at 3:02. Anyway, the best thing is to wait for the investigation.