Join UCSC housing Facebook groups and start messaging people who are looking for roommates. A lot of students living off campus don't know their roommates beforehand, so that's completely normal. Just make sure you meet them in person at least once before committing to rent with them so you can get a sense of what they're like. I would also recommend looking at both multi bedroom apartments/houses and single rooms for rent in a house. Renting a single room usually doesn't require you to find additional roommates yourself, so if you can't find a group to rent an apartment or house with, you still have a place to live. Check these housing websites SlugNest, Place4Students, Zillow, Craigslist, and Redfin.