i just googled really quickly and aparently, yes. Mega causes problems like all websites do. The best way to do it is to host it directly on itch itself. (says google.) I never uploaded anything on itch yet, so i dont know personaly and just share the info i found online.
sadly no. The normal update button doesnt work. clicking on the settings button doesnt work and choosing the download buttons in this post itself, one of the four that isnt external also doesnt work. I sadly dont know why though as the lack of the external tag would indicate that it is on itch io itself, so i dont know why it still gives me the same error.