I have these zip files from the purchase of that item:

I download them to my computer into my Download folder.

In Poser, I use the File-->Install from Zip Archive command.

I then select the runtime I want to install into, in this case I chose my 'Victoria4' runtime I already had.

I repeated this step for all 4 ZIP files.

I then refreshed my runtime and everything was there. I then pulled a V4 into my scene (or in my case I used a Saha-4 weightmapped version of V4) and navigated to the Poses-->Victoria4-->SAV-->Marina folder in my Library and it was seamless. Not sure what steps you followed.