That screenshot is showing the “core” folder from the parts library. The full library is the next level up. In your view, the “fritzing-parts-develop” folder, which should contain several folders. bins, contrib, core, obsolete, scripts, svg, user. The .fzb files are in the bins folder. As long as Fritzing is pointed to the fritzing-parts-develop folder as the parts library, it will find all of the pieces.
There is not quite enough information here about how you installed Fritzing, and where it is expecting to find files. The normal parts folder would be “fritzing-parts” (or just “parts”), not “fritzing-parts-develop”. However, if you start fritzing from the command line (terminal window), you can tell Fritzing where to get the parts. From your screen shot,
fritzing --parts "$HOME/Documents/Fritzing/fritzing-parts-develop"
should do the job. There are other ways of getting the same result, but that needs more information about how Fritzing is being installed and run. I am using Fritzing on Fedora, and I know of 3 different ways that can (typically) be used for the install and run, each with a different way to do this sort of fix generically. And I am not a linux expert.