Hey, I thought the installers knew what they were doing and DAZ 4 would know where to look. Obviously, some items not showing up means, no they do not. 
I tried moving the Content folder. That did not seem to work.
I uninstalled the missing stuff and reinstalled where they should go (DAZ 3D\Studio\My Library). That seem to help (some missing items showed up during the loadup), but I still do not see the Mystery Cave Set.
There are 3 files listed as part 1, 2, and 3, but when I downloaded them, but the actual file names are
12281_3_dpc_MysteryCave_3
12281_4_dpc_MysteryCave_4
12281_5_dpc_MysteryCave_5
I also found a file on the product page
12281_1_tx_MysteryCave_1
I (re)installed all the files as stated above and when I looked at the readmes they each have different files. It was not listed after the reinstall and I do not see it in Content Library under anything. I’m guessing it should show up as a Set.
On a side note, at what point should one consider Platinum Club membership? I picked up a lot of stuff during the last 2 sales and I’m thinking I could have saved even more.
Thanks