Microsoft Word EndNote Add-In
There is no Microsoft Word EndNote Add-In for Microsoft 365. You can only access the Microsoft Word EndNote Add-In on the Microsoft Word Desktop Application.
Once you have opened a Word document in SharePoint, you can select Editing then Open in Desktop App to be able to access the Add-In.
EndNote Files in SharePoint
All EndNote files can be stored in SharePoint. However in order to open an EndNote library, you will need to save the files on your computer first along with any associated data folder and files.
Once you save EndNote files onto your computer and make changes to the files (e.g. add new references to your library) you are no longer editing the original files saved in SharePoint.
Once you download EndNote files you will need to unzip the files before they can be opened by right clicking on the zipped folder then selecting Extract All.
