Which project is this for? This error can show up for a wide range of reasons. We haven't had any downtime in a while so it's more likely related to how you have configured your page or what you have uploaded.
Thanks for getting back to me. Just tried it again and got the same message. So basically I am creating a WEB GL app from Unity. Zipping up that folder and uploading the zip. I have a game on here already and tried to copy the same settings but sadly doesn't work. Here is a screenshot of my settings https://gyazo.com/9b1bef1ede1e08bda8bce668ca797387. The game is Infinite Drift. It does look different when I upload it compared to my other game as it has boxes I can tick next to the download which the other one doesn't. Ive tried checking the boxes but still doesn't work. Any help much appreciated.