Install steps
Grab the Steam / Itch.io package
Open the download and pick Steam / Itch.io. A one-time Cloudflare check may appear.
Open your Among Us folder
In Steam, right-click Among Us then Manage - Browse local files. On Itch.io, open the app, select Among Us and show local files.
Extract into that folder
Drop everything from the package into the Among Us folder. BepInEx and the ModMenuCrew plugin are already inside - nothing else to install.
Launch and press F1
Start the game. The first launch is slower while BepInEx builds its cache, then it is normal. Press F1 when CrewCore loads.