I need to submit a paper to a journal that uses a referencing style that's not included in EndNote's default list
There are thousands of referencing styles, and many journals insist on authors using thier own in-house style when submitting papers for publication. EndNote's default list contains over 5000 output styles (see Edit > Output Styles > Open Style Manager), but there are others available to download through the EndNote Output Styles webpage - including the JBI Database of Systematic Reviews and Implementation Reports and AGLC.
If the style you are required to use is not one of those in the EndNote default list, go to the EndNote Output Styles webpage (see link below), and search for the style using whatever information you may have (eg journal or style name, publisher etc). If the style has been registered with EndNote, you may download it.
Note: The EndNote Output Styles page conveniently contains detailed instructions on how to download the style to your EndNote Library.
Please contact a Liaison Librarian should you need more assisance.