I have no idea, you're the first person ever to ask me this. I just went to the downloads page myself and they all work fine for me. Might be something on your end or your country? Sorry, wish I could help. Try going to my Patreon page to this post and download it there:
Serenity 1.0 Public Release | N2TheFire on Patreon
Or, setup a free Gamejolt account and download it there as well:
(2) Serenity by N2TheFire - Game Jolt