By default, EndNote will only install the most commonly used output styles, like JAMA, BMJ, APA, Vancouver, etc.
If you are submitting an article to a journal that has a specific citation style, and you don't see that journal listed in the EndNote Style Manager, you may be able to download and install the journal's style from the EndNote website:
https://endnote.com/downloads/styles/
Note: Styles created for EndNote 8 and later are not compatible with EndNote 7 and prior. Not all journals are available, but more than 6,000 are.
Use the Style Finder to search for the full name of the style or publication. Once you've located the style you're looking for, save it to your desktop or other easy to find location.
Installing Individual Styles
Download the style you want to install.
Double-click the style file. It should open in EndNote.
In EndNote, go to “File Menu” and choose “Save As”. Replace the word “copy” with your style’s name and click “Save”.
Click on “File Menu” and choose “Close Style”.