It's actually fairly simple to use with PhsyFS that's a file system addon, not a physics addon
Here's what I have (trimmed out the error checking code)
You'll need to #include <allegro5/allegro_physfs.h> as well for this.
Note, you can rename your file anything you wish, like "MyGame.dat", no need to have "zip" on there if you don't want it so obvious.
Once this is done, all file loading will be from that file. I have folders in my ZIP as well containing graphics, sounds etc... so when I load them I use something like...
...and it will load the PNG "MyImage.png" from the "Graphics" folder inside your zip file.
Important, if you wish to access a file outside of the zip you need to al_set_standard_file_interface(); first, then do your normal file access, and when you're done, use al_set_physfs_file_interface(); to switch back to your ZIP.
Another way to do this, and probably a better one, is to use: