It's not uncommon. You're probably not going to work on anything serious until they get you one, but until then it'll be much more useful than a phone, when it comes to looking things up or viewing pertinent web pages or videos. Avoid putting any sensitive data on your laptop, as it likely won't be as secure as the one they set up for you. Even if it's a small startup, in California there's a bunch of bureaucracy around onboarding new hires. I joke that there's a small-business-industrial-complex that makes its income bleeding small businesses dry offering compliance services.

Fun fact: When you're new employer makes you read a bunch policy, or watch videos about them, it's called indoctrination. It literally means learning, but outside of business context it has a much harsher connotation.