I made a simple game in Processing, and tried to export it as an applet. It exported the files, but when I would try to run the applet in the browser, it would just be blank and wouldn’t load. The raw jar file wouldn’t run on my computer either.
I will answer my own question.
The solution was simple, and odd. When exporting, Processing creates an applet folder but does not include the assets needed to run the app or a changes to the paths for the required files. For example, images, audio, fonts etc.
So you need to put all the required files into the applets folder as well (or change the path definitions) manually.