Hello! Sorry to hear you encountered an issue, on that island there's a moving platform that can take you to the left island, did it not appear?
Also, the download version has a save feature, I allowed it for browser now too (it saved the game but didn't load).
The moving platform does not extend all the way to the bottom right island, so I cannot use that to access the island since the jump does not extend that far.
Also, I find those moving platforms to be evil. Some of them are far too small. In the south-most map, some of them kick you off when they come to a stop. Maybe extending the hitbox a little would help?