You can access SURFsharekit using this link. In the first screen select Inloggen, and in the second screen select Leiden University under Login with. Log in using your ULCN. 

You will subsequently be requested to review policies and your information that will be shared. If you consent, you can proceed to filling in your profile. 

In the first screen, select your position within the university. Optionally, you can change your name or fill in an alternative email address. 

Select which department(s) within the university apply to you; department Universiteit Leiden should always be included. Finally, select Volgende to complete your profile.