I can't run the update as it gives me an error:
"This title is hosted on an incompatible third-party website"
I think the best thing would be for you to delete it and download it again. The game is already too large, so we can't host it on itch. Delete the game file you have on your PC, just the folder where you have the executable, and download it again. Since it's still an early access version, we can't guarantee compatibility with previous versions.
I think I understand what is happening.
The game is too large to host on Itch.io itself, so you must use a third-party website to host the files instead.
But, Itch does not have any kind of relationship with this third-party website and does not allow downloads through the Itch.io application.
Meaning we can not use Itch to download and play your game, unless I'm missing something