What does my Ring camera actually do without an extra subscription?

I received a Ring tilt cam as a gift. I installed it and now I'm getting messages that I will need a special subscription to see the videos of people at my door. What does the camera actually do without a special subscription? What's the point of buying it when it doesn't seem like it does what I thought I was buying g it for? The website and app are very co fusing and unhelpful.