I happened upon this area while out exploring one day. I was already camping at a paid provincial campground but once I found this area I moved there next to give myself more time, free of charge, to keep exploring the nearby back roads.
I saw signs indicating that it is a public land use area and talked to fellow campers while there. It is a fairly popular spot in southern Alberta and there are additional sites down the main road from where I stayed, you just have to keep driving (and not far) as I saw others while out exploring..
Things to consider, there are no amenities. You are off grid. I had no cell service either. The campsites are loosely designated by the fire rings created by other campers and there are lots of ATV trails around so sometimes there is the noise of those riders going by.
Overall I found it peaceful and relaxing. The Castle River is very close and if you’re lucky you may even be able to land a site right on the bank. The sound of the river made my stay there amazing, even in late April’s rain.