Web version is run via the "index.html" file inside of the www folder. (It's kind of far down inbetween a bunch of .json files.) You want to open that file with your web browser. I highly recommend firefox for this, as I haven't been able to get it to work on chrome. (Unsure about other browsers.) You will also probably need to adjust your browser settings to let it read files from your computer. This link helps with that. https://www.reddit.com/r/RPGMaker/comments/dqvdqo/fix_error_failed_to_load_dataa...