Linux
You first have to install rustup. You can find the up-to-date instructions on rustup.rs.
Then install GTK 4 and the build essentials. To do this, execute the command belonging to the distribution you are using.
Fedora and derivatives:
sudo dnf install gtk4-devel gcc
Debian and derivatives:
sudo apt install libgtk-4-dev build-essential
Arch and derivatives:
sudo pacman -S gtk4 base-devel