Maybe check and make sure that the Default Poser Prefs file is pointing to the location of your content. You can edit it using TextEdit, and will find it in your Poser folder, ⁩ ▸⁨ Runtime⁩ ▸ ⁨prefs. 

Bit tricky to troubleshoot since I'm not sure where everything Poser 11 is on your system and where any new Poser 13 stuff might be.

However, if you are still doing everything from a Poser 11 runtime, and just installed Poser 13 for the app itself it might be as simple to fix as changing CONTENT_ROOT_PATH "/Users/Shared/Poser 13 Content" to CONTENT_ROOT_PATH "/Users/Shared/Poser 11 Content"

Poser scripts by Snarlygribbly