The useful first step at Denver International Airport is to treat the airport's own transportation page as the source of truth. After baggage claim, follow current rental-car signs and keep the destination---courtesy shuttle between Jeppesen Terminal and rental car agencies---in view rather than navigating to an unrelated public address.
At DEN, follow the airport's current rental-car signs from Jeppesen Terminal and confirm the pickup zone before boarding the courtesy shuttle. The airport's own rental-car guidance is the source of truth when terminal circulation or construction changes.
Before leaving the facility, confirm the agency's current hours, identification and payment requirements, vehicle notes, and return instructions. Photograph the vehicle condition and keep the official airport and agency pages available for the trip home.