I just tried preloading your ZIP file in a new experiment and it did download the archive, so you’re good on that front.
The problem comes from the structure of your archive: I downloaded it manually and opened it, and it appears to embed a folder ogg_test which itself contains the resource that you want to access (your OGG file). Try re-creating the ZIP file, but instead of archiving the folder containing your resources, directly select the file(s) that you want to include. You should see your resource files as you open your ZIP file, they shouldn’t be embedded in a folder within the archive.
Let me know if problems persist