You should probably reinstall. There used to be installer files available (along with the service releases); I'm not sure where they are these days.

The library won't work. I'm surprised it worked on your old machine. Basically, Flash is dead.  Adobe's decision.

There are some possible solutions. There's discussion here:

https://www.renderosity.com/forums/threads/2956792

The easiest solution might be to upgrade to Poser 11. It's cheaper (and more stable) than Poser 12, and doesn't have the Flash library issue.