You'll need the following dependencies:

• meson
• libeditorconfig-dev
• libgail-3-dev
• libgee-0.8-dev
• libgit2-glib-1.0-dev
• libgtksourceview-4-dev
• libgtkspell3-3-dev
• libgranite-dev >= 6.0.0
• libhandy-1-dev >= 0.90.0
• libpeas-2-dev
• libsoup-3.0-dev
• libvala-0.48-dev (or higher)
• libvte-2.91-dev
• valac

Run meson build to configure the build environment. Change to the build directory and run ninja test to build

meson build --prefix=/usr
cd build
ninja test

To install, use ninja install, then execute with io.elementary.code

sudo ninja install
io.elementary.code