itch.io

That error occurs when there is an issue with web browser settings. It's either a privacy, or security setting that is blocking cookies / caches.  

I found a couple articles that may be able to help you. 

https://itch.io/t/2173357/troubleshooting-game-launch-save-errors

https://itch.io/t/1698549/i-am-unable-to-save-my-progress-in-twine-games