The hide is at the posted coordinates, but you must complete the challenge before you can claim the find.
The challenge is to fill each difficulty row and terrain column with 150 or more caches. There is no time limit, caches can be found before or after this challenge was published, and can be from anywhere in the world. You may sign the log book at any time in anticipation of meeting the challenge in the future.
My current DT grid is attached as an image to show what a DT grid which meets the requirements should look like (see the highlighted numbers all above 150) and to demonstrate I have met the requirements of the challenge myself.
You can easily check if you meet requirements by looking at your statistics on Project GC or using the challenge checker below.
This is a difficult challenge (hence the D4.5 for this cache) but for those cachers interested to find a range of difficulty and terrain caches, it will be a rewarding experience to see those numbers increase (and perhaps fill your DT grid along the way). The terrain of this cache is around 2.