When you create a new library (a file of your references), make sure it is not saved to cloud storage like iCloud. Saving your library to cloud storage may cause issues.
As a current UQ student or staff, you have automatic access to OneDrive. Often, cloud storage is the default place where your library is stored.
To avoid this:
Watch Exporting to EndNote on Mac (YouTube, 1m39s)
The first time you open EndNote, only the toolbar will appear. You need to create a new library to open it fully.
You can use EndNote for footnote styles. You need to:
Note: It is generally not easy to change from a author-date or numbered style to a footnote output style.