Hi! Sorry to hear that you're still having issues.
I've had a look through the screenshots you took, and I think this is what's happening.
- The initial 403 message is because the index file (file that points to other files) associated with my game wasn't present. However, RenPy Web packages are like this by default, and they immediately point to a second file. Looking back through earlier screenshots you took, I can see that this is still working. When you tried clicking the link in the 403 message, you actually navigated to where your browser was looking for the index file on the itch.io server-- since you didn't have authentication to do that, it saw you as an "Anonymous Caller" and denied you access. I've manually relocated the index file so that this 403 won't show up in the future and cause anyone concern.
- "Uncaught Loading data file failed.Error" is the likely culprit. I've been unable to replicate it on a Linux + Chrome test machine though. The links you followed in the error message actually took you to the code to return the errors, not the errors themselves, which is unfortunate. I tried to do a search for the same error, but the only thing that came up for Itch or RenPy was your post, so I don't have much to go on.
I honestly still don't have a solution for this, sorry. It looks like it's on Itch.io's end, particularly with how your browser and their servers are communicating. If you have time, please try playing other RenPy games on the site and see if you run into the same issue. It'd be good to confirm where the error is.
Thanks again for your patience.