This is a multiplayer achievement. You must have reached Nice to be able to play Horizon Online.
After reaching Nice, buy and upgrade a couple of cars if you fancy from the Autoshow (R1, R2 and A class events are common in Horizon Online. There are cars on lend but you won't earn much XP and CR from using them) and then press Menu, and select the Online Road Trip option. This will find you a match. Stay in free roam until it finds one and accept it. Wait for the current event to finish, and then select your vehicle for the next one. Complete the road trip to unlock the achievement. You need to finish all four events, you can't join in progress.