This guide is for Ubuntu and Ubuntu-based distros. Most concepts will remain the same on other distros, but when installing packages, you will have to use your own package manager instead of apt.
Waydroid, as its name suggests, only works on Wayland, not Xorg. If you're on Gnome, then on your login screen, click the cog icon on the bottom and make sure the Xorg option is NOT selected. To verify this, run:
echo $XDG_SESSION_TYPE