The latest DAViCal release is generally available for download from:
Andrew's Web Libraries, which DAViCal depends on, is available from the same location.
See Developer Setup for cloning and running from git repositories.
Pre-built Distribution Files
Debian / Ubuntu
Jessie has AWL 0.55 and DAViCal 188.8.131.52, while Stretch has AWL 0.57 and DAViCal 1.1.5. Packages can be installed directly with apt-get. You may want to consider the backports repository for newer versions and bugfixes.
Raspberry Pi2 Raspbian
You can find a very detailed how-to here: Raspberry_Pi2_Raspbian.
DAViCal and AWL have been synced from Debian and are present already.
Older / Other DEB-based releases
While older DAViCal packages are present in several releases of Ubuntu and Debian, you may want to consider installing the most recent version to benefit from bug and compatibility fixes. For this purpose, we maintain a davical-current repository, which can be added to your sources.list through a three-step process described at https://people.debian.org/~fsfs/davical-current/setup.sh
An ebuild should be available within the 'sunrise' overlay.
Red Hat and other RPM-based releases
It is possible that DAViCal will appear in the Fedora repository at some point. In the meantime, it is probably best to install from the sources.
There are ports of DAViCal which are updated from time to time.
Installing from Source
DAViCal is not a compiled package, so there is generally very little to be gained from installing from source, however you can do this by downloading the relevant .tar.xz files (both DAViCal and AWL) from the above location.
Installing from Git
If you want to follow the cutting edge and help develop and test DAViCal, you can clone from the above mentioned gitlab repositories as follows: