You should still try to credit the assets you use, but just in case you're interested in the pack now, this has been updated to a very permissive license. (IMO, CC0 is too permissive for a paid pack, bad actors could take advantage of those terms)
I do recognize that CC0 might be too permissive for something of this scale, but i wanted to give as much freedom as possible without having too much in the way.
