itch.io

That means that itch.io version is no longer supported and you should ask for a refund. You can download Among Us by searching on MediaFire or Mega

The PC version of Among Us on itch.io is currently not being supported. Prior to their roadmap, they claimed they intended to resume support in future, but the roadmap makes no mention of this and nor have the devs made any comments affirming it to still be an intended goal in future.

If you bought the game here, the download page also has a Steam Key - you can, if you're willing and able to use Steam (there are a number of reasons why people can't or won't), you can enter the code into your Steam account and get access to the game on there.

If you don't have that option, then as Trollify said, get a refund. But unlike Trollify, I'd recommend picking the game up on mobile where it's free without breaking the law to make it so, or pick it up on the Epic Games Store (which isn't very good, but for some people, still better than Steam)