Signed up for my first block tomorrow, how does it actually work?

Picked up at 7am to 330pm block. My area says any size car can work so I am driving my sedan since the subaru outback is out of commission.

I just arrive there at 7am and say I am here, then it gives me a route? It says I may have to come back and pickup more items and it also says it might have me delivery other items. What has been people's experiences using smaller vehicles for this?