There are different ways to Download Among us, few of them are paid few of them are free.
You can download and install on different platforms, but it depends how and where are you Downloading Among us. If you want to play Pirated version of Among us, you can download it but unfortunately you can not play online with friends, and playing solo without friends or without lobby there is no point of playing.
But the good news is you can play free as well by other ways, of course on Computer as well. If you want to know the procedure you can follow THIS LINK.
This procedure is totally free and very easy to set up, you can ready the game within few minutes.