You'll need the following dependencies:
- libadwaita-1-dev >= 1.0.0
- libecal1.2-dev
- libedataserver1.2-dev >= 3.45.1
- libedataserverui4-dev >= 3.46.4
- libfolks-dev
- libgee-0.8-dev
- libgeocode-glib-dev
- libgeoclue-2-dev
- libglib2.0-dev
- libgranite-7-dev >= 7.7.0
- libgtk-4-dev >= 4.12
- libical-dev
- libportal-dev
- libportal-gtk4-dev
- libshumate-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