I couldn't get a ride.
He/she could not find someone to take him/her to class so he/she got there late. Ride in this context implies (suggest) that it's a car.
Basically, it means they were unable to find transportation. They couldn't find a bus or train to ride to class. They also didn't have access to a car to ride in. Another way it is often used is: I gave my friend a ride. Which means that I drove my friend to wherever.