$37.2m on a $153m post? That's a pretty big chunk of the company to give up. Looks like A16Z is going big on these guys. They're awesome, so that's great news!
Most VC's want 20%-25% ownership. And DigitalOcean is a very capital intensive tech company, needing to buy/build machines, pay for electricity, rent rack space, and pay for bandwidth. Virtually all tech startups on the other hand just need to pay for writing software and renting said machines/hosting.