In EndNote, click on Edit>Preferences (Windows) / EndNote>Settings (Mac) and then click on Find Full Text:
Copy the below link and paste it in the OpenURL Path field:
https://sun.alma.exlibrisgroup.com/view/uresolver/27US_INST/openurl?
Copy the below link and past it in the URL field:
https://ez.sun.ac.za/login?url=
Then click on Apply.