Click the Team Members button at the bottom left of the menu bar
Click the +Add Team Members button in blue at the top right of the screen
Copy the URL by clicking the Clipboard button to the right of the URL or copy by right click.
Send link to user you would like to add as a team member
User will be given 60 days to create a profile within Synapse. Admin will then be able to assign the user to an Admin or User profile based on what level or controls the user should have.