You can't open your game? These instructions are all I know for now:
PC: Unzip the folder and open this file; C:\Users\(your pc username)\Downloads\among-us-windows\AmongUs
If no UnityPlayer.dll file exists within the folder or the folder is zipped, the game won't start.
Mobile: Download the game from your device's app store and open it once the game is downloaded to your mobile hardware.
Did I solve your problem?