Content that you purchase from Renderosity can be installed from the library. 

"Uninstall" the copy that you placed in the Downloads folder. (That is, you'll probably need to manually remove the geometries, library files, and textures).

Open the Poser library. Click the Purchases tab. Then select the Renderosity radio button.

Enter your Renderosity user name and password and click Login.

The library will list all of your Renderosity purchases. 

Find the product you want to install, and click the Install button.

After the product is installed, you'll need to expand the Purchases folder in the library window to find your products.

NOTE:  Products will only show up as "installed" if you install them to this Purchases folder. If you've already installed purchases in other runtime folders, you'll see an INSTALL button instead of an UNINSTALL button beside the product in the Renderosity purchases library folder..

Also a word of advice ... if you have hundreds or even thousands of Renderosity purchases, you may not want to click the Install All button. It's a long wait. LOL