git clone ... takes too long and you just want to checkout one revision (i.e. you don't want all the history) of the repository, do this:
git clone --depth 1 protocol://path/to/repo
As from this answer on StackOverflow. This gets you the latest commit, without history. It's still gonna take you a long time, as it appears to be the whole Linux kernel...
A regular clone is a repository with all its history and commit messages. The ZIP-file just contains the state of the repository at a single commit (snapshot) without any history. This
--depth option provides you a way to do this with Git without the need for a ZIP file for every commit.
About the ZIP-files on Github in particular. If the developer of the repository determines to tag a specific commit (i.e. puts a label with a nice name on the commit hash like "version 1.0"), the contents of the repository is made available as a ZIP/TAR file on Github for your convenience. There should be no difference between the two, besides the version of it as the clone command is likely to give you a newer (probably experimental) version.
To make things more complicated, but necessary to be correct in this answer, the clone only checks out the default branch, whereas the ZIP-file on Github may be created from a tag in another branch (release for example).
As stated in the comment, further instructions on how to install this particular piece of software is documented very well in the