You'll need the following dependencies:
- libchamplain-0.12-dev
- libchamplain-gtk-0.12-dev
- libclutter-1.0-dev
- libecal1.2-dev
- libedataserverui1.2-dev
- libfolks-dev
- libgee-0.8-dev
- libgeocode-glib-dev
- libgeoclue-2-dev
- libglib2.0-dev
- libgranite-dev >= 5.2.0
- libgtk-3-dev
- libical-dev
- meson
- valac
Run meson build to configure the build environment. Change to the build directory and run ninja to build
meson build --prefix=/usr
cd build
ninja
To install, use ninja install, then execute with io.elementary.calendar
sudo ninja install
io.elementary.calendar