Shot in the dark, and well if its everything this probably isn't is...was some of the poser content installed with an installer file by chance?  Perhaps they hardcoded the install path vs using ":Runtime:Textures:...."  can you look in the source files

Another thing are you loading the file that was already setup with poser content or trying to place things in a new scene (Do things work if you place things in a fresh scene).  Try saving out the file in a .car but not compressed and then you can look in the .car file and see what it is using for the paths.

This is the first .jpg referenced in a new .car file when I loaded the troll and applied the Lava map.

TMap {
Apth "D:dazext-contentRuntimetexturesDAZCharactersTrollLavaEyeM.jpg"
Rpth ":::daz:ext-content:Runtime:textures:DAZ:Characters:Troll:"
Ffmt JPEG

It should use the Rpth (relative path) but I am not sure what it will show on the mac, if it will have the volume name encoded or the systems lower level unix volume path.  If nothing else we could be exposing a problem that could be addressed.

Lastly is it every texture or just a few, if you import content into a new scene on the new system does it have the same problem or just content saved before then opened on the new system?