If you are working on a project with someone and both need to be able to access the same references, you can share a group of references in EndNote. Note: This will only share the information about the reference, not any attached files.
Once you have grouped the relevant references (see Organizing Your Library if you haven't yet created a group), you can share that group with someone else. Go to Organize -> Manage My Groups
Click Manage Sharing next to the group you want to share.
Click Starting sharing this group.
Enter email addresses for your collaborators, decide if they should be able to edit the references or not, and click Apply. Note: use the email addresses they use to log into EndNote.