• In Mendeley Desktop, go to the "View" menu, "Citation Style", "More Styles..."
• Drag and drop the downloaded style onto the style list

You can also use Mendeley's own version of this CSL Editor at //csl.mendeley.com, where Mendeley will host your style, install it directly to your computer and help you share the style with other CSL users.

Go to "Preferences...", "Cite", "Styles", click the "+" button and select the downloaded style.

See also the official Zotero documentation.

See the official instructions for Papers 3 for Mac or Papers 3 for Windows.

Copy the downloaded style file into Docear4Word's style folder. This folder is usually located at "C:\ProgramData\Docear4Word\Styles\".

If the folder "C:\ProgramData\" isn't visible, you need to configure Windows to show invisible files. To do so, open the Windows Explorer, press Alt, select "Tools" -> "Folder Options..." -> "View" -> "Hidden files and folders" and select "Show hidden files, folders, and drives".

See also the official Docear4Word documentation.

• Open Paperpile
• Go to "Settings > Citation Styles > Custom styles", click the "Upload CSL file" button and select the downloaded CSL file.
• The newly added citation style will be listed in the "Custom styles" section on successful upload.