Try not to clutter your Poser installation. Keep whatever you can on a non-system drive, just link/un-link those product folders through 'external library' when needed.

A lot of the old models did not have 'correct' runtime folder trees. May be worth crafting an un-populated one of your own, ready for copy/pasting stuff.

This also helps if you collect and convert models from other formats, such as DS/DUF, SFM, XPS and PMX. As yet, I can only import 'rigged' as FBX, albeit warily...

You got RSR thumbnails ? You need the totally classic Dizzi converter...

https://www.renderosity.com/freestuff/items/57197/rsr-to-png-converter

I'm still finding and untangling some of the early DS figures / outfits that came as self-installing EXE files. Some may be opened as 'archives', most must be wrangled to have sight of Poser, then shunted onto data drive. Many only have RSR thumbnails, so I knew what you needed...