There may not be an easy fix, I'm afraid. The problem people run into with Poser 8 is that it used Flash for the library. Some people got it to work by installing an old version of Flash, and applying the latest updates to Poser 8, but that is a security risk, and not recommended. Flash is going away very soon anyway.

You could run Poser 8 without the library, using Explorer instead. It's clunky, but it works.

Another issue you might run into is that Windows 10 doesn't like the runtime installed where Poser used to install it, in Program Files. If you put it somewhere else, that should fix it.

Upgrading to the current version of Poser is probably the best thing to do. You can try it free for 21 days, and there's upgrade pricing.

https://www.posersoftware.com/downloads