Can teens go to uni?

They have to be young adults.

From the Q&A with SimGurus:

Do the unis have open day type events for teens to explore and decide their future?
Teen Sims may visit the university campus and all its buildings, but there are no specific open day/recruitment events for teens.

How can teens prepare for university?
Teens can prepare for university by increasing their Skills and applying for scholarships. Teens can also apply to university a bit early, allowing them to enroll right when they age up to YA and become eligible to.

How/when do sims apply for uni? Can you apply for both unis and wait to choose or do you have to choose before applying? Can you be offered a university place or scholarship without even applying if you have high skills/grade etc? (e.g, a teacher applied on your behalf)
Sims can start applying to universities about a week before they age up into a Young Adult. Every application goes to both universities and you may choose which university and which degree to pursue once your Sim gets their acceptance letter. Sims will need to apply before they can enroll in university classes but may be offered scholarships they didn’t apply for if they are accepted into enough distinguished degrees.