I'll be honest with you I wasn't even aware that the our art files and such were protected until you mentioned it. Though I did a little digging and it's because we have files set to be classified upon building distribution!
Here's the Ren'py documentation for it You can insert the lines of code that is shown in the documentation into your project's options.rpy.
Though honestly I really just learnt what this meant because I used https://feniksdev.itch.io/easy-renpy-gui as a starting point and built on top /modified everything. The easy ren'py gui's option file has all the classify lines already scripted out. Definitely recommend checking it out even to see as an example!