I finally got Poser 13 to install after messing with lots of folder and drive permissions plus installing as Administrator on my laptop.  The last Windows 11 update did a number on my permissions.  I can't even do Cut/Copy/Paste from my usual folders.

Helpful tip - after you get Poser 13 installed and the software asks for the serial number, don't use the caps lock. Just type the letters lower case.  Don't forget the hyphens (-).