When I download add-ons from this page, sometimes I get a zip file, but sometimes it's just a link like this.
I don't have programmer training, but I know that's something to do with calling an action from the console. Before I just copied the text into a text file, saved it as a zip and installed it that way, but what's the actual way to get the add-on from a link like that?
I saw this: How can I get a list of the installed addons using the API? but it doesnt help me.
The wiki pages for addons are in need of an update. The list on the first page you refer to is listed in three columns, the first lists addons that are included with each blender release, the middle column are included in the addons contrib repository and the third column are maintained by users with each addon available from their own repositories or download locations.
Where a contrib addon has a download url starting with https://svn.blender.org/svnroot/bf-extensions/contrib/ - which is blender's old svn repository - it can now be found at https://developer.blender.org/diffusion/BAC/ - provided it hasn't been removed for some reason.
It can be a bit awkward to download multiple file addons through the developer.blender.org site. If you don't want to install git and follow the checkout instructions on the contrib page you can access the git repository through the gitweb interface to download a snapshot of all or part of the contrib repository.
You can use wget which is a command line tool to retrieve files using HTTP, HTTPS and FTP you can download it from here and these are the installation instructions and how to use
Also rather than coping it to a text file you could have right clicked on each of the six files and clicked 'save link as....' (a easier way) after that just put all of them in a folder and put that folder in the add-on folder
