Download Thunderstore Mod Manager. You can change the destination if you want, but that's not required. Once the download and installation is finished, open Thunderstore Mod Manager (There should be an icon on your desktop, if not then check around in AppData).
Search for Among Us on the supported games list. Click Select game & select the platform that you're using to play Among Us, then wait for it to load the mod list.
On the Profile Selection page, you can use the Default profile, or create a new one specifically for TOHE. Click Select profile, and use the sidebar to find Get mods.
Search for TOHE. Click the option by: TheEnhancedNetwork as this is the official version, and click Download. Once it finishes, use the sidebar to find My mods.
Near the top of your screen, click the Modded option. (Clicking Vanilla will launch Vanilla, self explanatory.)