You must create an EndNote Online account in order to use tools such as syncing and sharing. Create an account here.
More information on EndNote Online can be found in the Clarivate EndNote Online Guide.
You can sync one EndNote Library to be able to access your work across multiple locations.
EndNote library sharing allows you to share your library to work more efficiently with peers.
A tool that can be used through EndNote Online, to help identify relevant and useful journals when considering where to submit your manuscript.
Read more about it here.