You can only log in to Studielink and submit an enrolment request if you have a DigiD account.

Make sure that you apply for your DigiD account in plenty of time, as it takes around 5 working days from submitting your application before the log-in details are sent to your home address. If you do not yet have a residential address in the Netherlands at the time of registering, you cannot apply for a DigiD account. You should then select the option "Request log-in details and log in" at www.studielink.nl.