I replaced everything with the PNGs but it still doesn't work. Here is the new error code
Viewing post in Shuffling 20 Cards in GB Studio 4 comments
Okay, I disabled the references to the audio files (since those are not available).
If you can clone the repo that will be the quickest and easiest way to test if this fixes the issue for you. Alternatively, you should be able to download the Memory-GBS4.gbsproj file and replace the one you have currently.
Let me know how this goes for you!