The specs are quite OK for fallow / whitetail size. 200kg max load, 100m wire rope, 18m per minute. Problems start there, because they don't tell you what most numbers mean (min/max/average). Since the drum has several layers of rope, the performance will vary a lot.
The most important information, how much energy it takes to drag is missing. Also electric screwdrivers are not meant for that kind of job, and will probably cook off in short time. On the other hand required torque is low (4Nm) but several minutes of constant running will heat the screwdriver up anyway. I'd also try to construct some kind of holder for the screwdriver to keep it in place.
Also the video is one year old and the website still shows "new product" and there is no price or availability info.
Regarding the pulley system, best way to "work" for human is using your legs. In this case walking. Try to use odd numbers for advantage, meaning you would walk the opposite way to the dragged animal. I think 3:1 would be sweet spot. That way if you drag uphill, you'd be walking downhill. Keep the pulley system somewhat short, I think max. 20 meters (you'd be walking 60m for single leg of the drag). Construct short sections of rope that are same length, or long rope that has loops with the same interval. So that you can reset the pulley system and attach it to new drag point without extra walking along the line. I think it'd be best to use vehicle as anchor point, and keep the pulley system on the same end as the dragged animal. That way you can address all the problems like snagging.